Keep both time formats

The CUC time format has been added to the `TimeHelper`. So, we have two possible time formats: the CUC (TAI compliant) and the CDS (UTC compliant), that are described in [CCSDS 301.0-B-4 ](https://public.ccsds.org/Pubs/301x0b4e1.pdf).

See merge request acubesat/obc/ecss-services!36

Automatic per branch, code coverage report and documentation generation

## Summary
In this request a page deployment job is added to CI settings, which takes care of the automatic, per branch, generation of the code coverage and the doxygen based documentation.

## Implementation details
To generate the code coverage reports, two main additions where needed. First the `set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -O0 -Wall --coverage")` compilation flag was added in the `CMakeLists.txt` file, in order to generate the tests with no optimization and also add the necessary coverage - `.gcno` - files. The second addition is the [`gcovr`](http://www.gcovr.com/en/stable/) package, which is a python based package to generate code coverage reports and create the html page.  
In addition to code coverage, in this request the automatic generation of the doxygen documentation is also implemented.  
Once this is merged, there will be one page per branch for the documentation and one for the coverage report. The pages will have the following form:  

**Coverage:** `https://acubesat.gitlab.io/obc/ecss-services/coverage/<branch-name>/`  
**Coverage in master:** `https://acubesat.gitlab.io/obc/ecss-services/coverage/`  
**Documentation:** `https://acubesat.gitlab.io/obc/ecss-services/docs/<branch-name>/`  
**Documentation in master:** `https://acubesat.gitlab.io/obc/ecss-services/docs/`  

## Future improvements and ideas
* The coverage page look can be improved using custom styling, so one goal is to improve the coverage page look.
* Add a welcome page in the root page `https://acubesat.gitlab.io/obc/ecss-services/`

## Update (05/04/2019)
Major improvements have been made since the creation of this merge request. Code coverage is now generated by using two tools, [`gcovr`](http://www.gcovr.com/en/stable/) and [`lcov`](http://ltp.sourceforge.net/coverage/lcov.php). They are used together to compare each other and also generate a better version of the code coverage. Adding to that, the coverage argument hασ been moved from the `CMakefile.txt` to command line arguments like `cmake . -DCMAKE_CXX_FLAGS="-g -O0 --coverage"`.

See merge request acubesat/obc/ecss-services!34

- Improved the overall look of the page
- Coverage generation using lcov and gcov
- Using less gitlab server page by removing interjob artifact generation

Execute TC packets

Closes #31. Actually, `execute()` functions receives as input TC packets and they call the proper services'          functions that have been implemented to handle TC packets.

See merge request acubesat/obc/ecss-services!35

Keep consistent the declaration of the execute functions in all child classes and change the scope of the execute function in the MemoryManagementService

Ecss st19 array replacement

etl::map was used to replace the array that was used to store the EventActionDefinition struct. 
Also, in this branch ErrorHandler error throws were added.

Thanks to @lightspot21 for the input.

See merge request acubesat/obc/ecss-services!33

# Conflicts:
#   inc/Services/EventActionService.hpp
#   src/Services/EventActionService.cpp
#   src/main.cpp
#   test/Services/EventActionService.cpp

Merge branch 'ECSS_ST19_array_replacement' of https://gitlab.com/acubesat/obc/ecss-services into ECSS_ST19_array_replacement

Merge branch 'ECSS_ST19_array_replacement' of https://gitlab.com/acubesat/obc/ecss-services into ECSS_ST19_array_replacement

Changed comments

Fixed names in ErrorHandler and enumeration of errors and removed explicit declaration of true or false in a CHECK

- changed variable names
- added breaks
- corrected a comment
- deleted explicit declaration of true/false in ifs
- fixed a bug in tests caused by passing the message by reference