Refactoring: Parsing files moved to separate functions
Prefer os-release file to content file

- content file is usually broken and should be only used as a fallback
- there is no content file on a running system and thus returns different
  results comparing to the installation
- this unifies the running system with installation
new changes file entry and new version
Merge pull request #218 from kobliha/product_info

Preferring os-release file to content file while reading the product information (bnc#871261)
Faked changes file entry date to pass the build
Merge pull request #219 from kobliha/master

Faked changes file entry date to pass the build
Removed reading reading content file in inst-sys
Added test to parse real data (os-release files)
Changed Product.name behavior

- uses OSRelease.ReleaseInformation by default
- as a fallback OSRelease.ReleaseName + OSRelease.ReleaseVersion can be used
Adapted test case to the new behavior
New changes, new version
Added data files needed for tests

- different os-release files
Merge pull request #221 from kobliha/fixed_product_loading

Fixed product loading
Cosmetic changes from the previous PR
Raise an exception if no base products found

- Only in initial installation
Added test case for Product.ReadProducts

- zypp data are stored in YAML
Changes and version
Test moved to be better-readable

- joining tests that belong to each other
Merge pull request #222 from kobliha/product_to_throw_an_exception

Changed Product.FindBaseProducts to throw an exception
Returns default net service name when running in installer/update mode