interface: Added SMART test results to OSD interface
servers: Added smart script parameter to OSD config.
servers: Added SMART test result to OSD ServiceData.
servers: Added OSD smart health test result to DIR status page.
servers: Added check of OSDs SMART test results to default OSP
servers: Fixed error in default OSP.
interface: Changed Smart Test Result to OSD Health Result and added WARNING as possible result.
servers: Changed parameter name from smart_script to health_script.
servers: Added color highlighting to OSD health status in DIR status page.
servers: Updated default OSP. An OSD with "warning" as health status is now treated as unhealthy.
servers: Renamed smart_health_test to osd_health_test.
contrib: Added osd health example script. The script supports RAID and single device configuartions.
servers: Improved exception handling in osd health status code.
doc: Added description of OSD health monitoring and health_script parameter to xtreemfs userguide
servers: Added health_script parameter to osd config file.
Merge pull request #334 from xtreemfs/jdillmann-junit3to4

Migrate JUnit 3 tests to JUnit 4
server: fixed javadoc
server: fixed javadoc in libxtreemfs interfaces
server: removed obsolete javadoc
tests: Use xtestenv for travis-ci unit tests.

The C++ unit tests are dependend on a running XtreemFS environment. Running the
tests within the xtestenv ensures it is available.
To be able to distinguish between C++ and Java failures, the xtestenv has been
extended to write the test results to a json file.