feat(Utils): Add method to retrieve module version

[Hipska]

Base information

Question	Answer
Related to a SourceForge thread / Another PR / Combodo ticket?	N/A
Type of change?	Enhancement

Objective (enhancement)

Helper method to easily get installed version of a module in iTop.

Proposed solution (bug and enhancement)

Added GetModuleVersion method to Utils class. In the meantime consecutive calls to the CheckModuleInstallation method for the same module will be faster as the result is now cached.

Checklist before requesting a review

• I have performed a self-review of my code, and that it's compliant with Combodo's guidelines
• I have tested all changes I made on an iTop instance
• I have added a unit test, otherwise I have explained why I couldn't
• I have made sure the PR is clear and detailled enough so anyone can understand the real purpose without digging in the code