Improve project root identification customization.
Merge pull request #299 from thomasf/project-root-parent-override

Support parent project root files which overrides current directory.
Added open in dired mode for helm-source-projectile-files-list
Merge pull request #306 from danielwuz/master

Added open in dired mode for helm-source-projectile-files-list
Always return absolute path from `projectile-project-root`

Fixes #305
Rename tests that don't follow `projectile-test-*` convention
Merge pull request #307 from Silex/master

Always return absolute path from `projectile-project-root`