Merge pull request #5 from vreixo/master

Fix #4 - Added new values to enum in RelativeDirection
Fix #6 - Changed type of message for PlannerError to plain string, to
resolve problems mapping with Jackson.
Merge pull request #7 from vreixo/issue6

Fix #6 - Changed type of message for PlannerError to plain string.
Create README.md
Update README.md
Add a Bitdeli badge to README
Merge pull request #8 from bitdeli-chef/master

Add a Bitdeli Badge to README