Add unit tests for #hash methods
Fix Duration#hash implementation
Merge branch 'features/hash-methods'
Bump version to 0.6.0
Add decimal fractions to all components in durations
Add tests to verify every duration component accept comma (,) as a decimal separator
Add constrain so fractions are only allowed in the last component of a duration
Update changelog
Merge branch 'features/decimal-fractions'
Bump version to 0.7.0
Add a Contributing section to the readme