cylc gsummary: ISO 8601 updated time

Display timezone.
 #982: prehistoric/futuristic cycling tests.

This adds tests for prehistoric/futuristic date-time cycling and also
date boundary behaviour.
update isodatetime to 2014.08.0-8-ga7f42b1
update graph test
#982: fix reference logs
Merge pull request #1111 from matthewrmshin/fix-cylc-gsummary-updated-time

cylc gsummary: ISO 8601 updated time
Merge pull request #1116 from benfitzpatrick/982.test-date-rollover

#982: test prehistoric/futuristic cycling, out-of-bounds year