Fixing turning tools on or off
[refs #31] Adding support for checking single files
Updating changelog with several new features and bug fixes
Fixing unit test to match new behaviour for deciding whther a tool is enabled or not
[refs #31] Updating documentation to include information about single files
Adding documentation on how to contribute to prospector
Bumping dodgy requirement version to get the Windows path bugfix (https://github.com/landscapeio/dodgy/issues/2)