added support for slurm 2.6 (ran tests agains cartesius)
Merge pull request #201 from NLeSC/feature/slurm-2.6

added support for slurm 2.6 (ran tests agains cartesius)
Fixed bug in sftp cache of SSH adaptor. Increased sleep time in generic job cancel test.
Fixed bug in generic file test.
Added missing file and dir cleanup to generic file test 20b.
Added FileTestConfig.readOnlyPosixPermissions. Fixes #198
Fixed getLocalFileSystems on Windows and added test FileUtilsTest.testGetLocalFileSystems. Fixes #199
Merge branch 'develop' of github.com:NLeSC/Xenon into feature/gftp