Workaround to TestFileChannelRestart failing on Travis CI.

See https://travis-ci.org/Stratio/flume/jobs/36775304#L6186
This exceptions seems to occur occasionally but it should
be inocuous.
Fix TestLog.doTestMinimumRequiredSpaceTooSmallForPut.

Travis CI had problems executing this test as is:
https://travis-ci.org/Stratio/flume/jobs/36758319#L6178