rose.fs_util: symlink: fix logic.

Do nothing if correct symlink target already in place.
Merge branch 'master' into fix.fs_util.symlink
Merge pull request #750 from matthewrmshin/fix.fs_util.symlink

rose.fs_util: symlink: fix logic.
rose: use Python to do "readlink -f" if necessary.

"readlink -f" is GNU extension.
metomi/rose#753: training course
metomi/rose#753: tidy training info
rose: remove unnecessary logic.

No need to cannonize a path twice.
Beginnings of clock triggered tutorial.
Merge pull request #754 from matthewrmshin/readlink-f

rose: use Python to do "readlink -f" if necessary.
Merge remote branch 'upstream/master' into clock-triggered-tutorial
t:rose-suite-log: tests for "rose suite-log".

Local jobs only.
t:rose-suite-log: test suite with remote job hosts.

In addition:
* Some configuration adjustments.
* Some None exception bug fixes.
Further fleshing out and skeleton of tutorial slides.
rose test-battery: now just a wrapper of "prove".
rosie.db tests should now be portable.
t: refactor.

Add TEST_SOURCE_DIR to common header.
Ensure all tests are run correctly.
rose test-battery: document update.
15-minute examples added to tutorial.
metomi/rose#753: update following feedback
t: suite tests: reduce timeouts.