Fixes to xfs_info parser - now passes all tests
Fixes to xfs_info parser - now passes all tests

* Sections are optional - fix in regular expression
* Regular expression library is 're' not 'r'
* Use class attributes for regular expressions
* Don't repeat section name in a variable - only used once
* re.findall() returns tuples rather than named groups
* Commented out warning when parsing doesn't match a line
* Added representation string for niceness

wcmitchell/insights-core,PaulWay/insights-core,PaulWay/insights-core,wcmitchell/insights-core