Improve support for multi-module projects

Fixed an issue when calling speedy-spotless:staged from a child maven module whereby the Git repository could not be found.

Update dependencies and improve tests

Tests are now run as part of the maven build.

Fix "Bare Repository has neither a working tree, nor an index" issue

Fixes issue where a "Bare Repository has neither a working tree, nor an index" message was thrown by JGit.

Also, updates JGit and Spotless to latest versions, and bumps version number for Speedy Spotless to 0.1.1.

0.1.0

Target Java 8