Fixup Scm and its test.

Support environments like travis-ci with no proper user config:
  setup a repo identity in test
Fixup _get_remote implementation (kill quoting) and test.
Spread testing to python 2.7 and java 6.
Use a multiline string for the script.
Cleanup custom node naming scheme facility to just concentrate on names.
Be resilent to lack of a configured SCM.
Merge pull request #139 from jsirois/jsirois/fix_scm_tests

Fixup Scm and its test.
Merge remote-tracking branch 'twitter/master'
WorkUnit and RunTracker concepts for pants.

WorkUnit represents a unit of work, for the purpose of tracking and timing.

RunTracker keeps track of all the work in a single pants run.

Auditors: markcc
A periodic thread.

Runs the thread's action at a fixed time interval.

Auditors: markcc
A clarifying comment.