[IMPROVEMENT][FIX] Get commit hash and compilation date when built using CMake.

[saurabhshri]

In raising this pull request, I confirm the following (please check boxes):

• I have read and understood the contributors guide.
• I have checked that another pull request for this purpose does not exist.
• I have considered, and confirmed that this submission will be valuable to others.
• I accept that this submission may not be used, and the pull request closed at the will of the maintainer.
• I give this submission freely, and claim no ownership to its content.

My familiarity with the project is as follows (check one):

• I have never used CCExtractor.
• I have used CCExtractor just a couple of times.
• I absolutely love CCExtractor, but have not contributed previously.
• I am an active contributor to CCExtractor.

---

Make available information such as Compilation Date and Git Commit Hash in the program.

Before :

ccextractor --version
CCExtractor 0.85, Carlos Fernandez Sanz, Volker Quetschke.
Teletext portions taken from Petr Kutalek's telxcc
--------------------------------------------------------------------------
CCExtractor detailed version info
	Version: 0.85
	Git commit: Unknown
	Compilation date: Unknown
	File SHA256: 52ca7853b4e37a17e6bae41984610b1d38ca6281d6b99ac020668ffc6a2f7391

After :

ccextractor --version
CCExtractor 0.85, Carlos Fernandez Sanz, Volker Quetschke.
Teletext portions taken from Petr Kutalek's telxcc
--------------------------------------------------------------------------
CCExtractor detailed version info
	Version: 0.85
	Git commit: ce0fc1b423ef2d4a83953b80bc32b5ccfd776f00
	Compilation date: 2017-08-12
	File SHA256: 52ca7853b4e37a17e6bae41984610b1d38ca6281d6b99ac020668ffc6a2f7391