[kinetic] Fix BFL include directories

[stwirth]

Closes #96.

Tested both scenarios mentioned in #96:

• Having bfl in the same workspace
• Having ros-kinetic-bfl installed

[stwirth]

The build failed with

19:28:46 INFO: Starting to record.
19:28:46 INFO: Processing GoogleTest-1.8
19:28:46 INFO: [GoogleTest-1.8] - 12 test report file(s) were found with the pattern 'ws/test_results/**/*.xml' relative to '/home/jenkins-agent/workspace/Kpr__people__ubuntu_xenial_amd64' for the testing framework 'GoogleTest-1.8'.
19:28:48 ERROR: Step ‘Publish xUnit test result report’ failed: Conversion error: org.xml.sax.SAXParseException; lineNumber: 2; columnNumber: 1; Premature end of file.
19:28:48 Setting status of e226d0d5d06e9b358e7a064f0444bcef3958ecae to FAILURE with url https://build.ros.org/job/Kpr__people__ubuntu_xenial_amd64/6/ and message: 'Build finished. '
19:28:48 Using context: Kpr__people__ubuntu_xenial_amd64
19:28:49 Finished: FAILURE

which I don't think is related to this change. The build of the packages and tests goes through fine.

[stwirth]

ping @DLu :)