Fixed a bug: In utcTime function, when the year was leap year, the extra day was substracted two times instead of one.

Added a function that converts elapsed seconds since Unix epoch to UTC date and the mission-specific function has been implemented

TC parser

See merge request acubesat/obc/ecss-services!16

Ecss st 05 enable disable

See merge request acubesat/obc/ecss-services!12

Changed tests for these functions

I was really proud of my commits today, vera loved them. But the dreaded moment has arrived comrades.

# Conflicts:
#	CMakeLists.txt

Added some subservice observable 6.5.6 of the standard.