Refactor Merge test to remove thing that don't need to be tested there

 - Checking that the parsing was done correctly has its own test
Add Tests for merging sections operations
Add tests for KeyData merging operation
Refactor & extend Merge operation so it works on Sections & KeyValues
Merge pull request #50 from rickyah/feature/allow_merge_section_and_keys

Refactor and extend Merge operation so it works on Sections & KeyValues