Fix demos to accommodate new api changes.
Move ipcluster.py and purge_cluster.py to utils/
Add iopubwatcher.py to utils/
Reflect utils move in Makefile.
Omit coveralls checking the externals directory.
spell externals correctly
Correct omits in coveragerc
Merge pull request #271 from cowlicks/fix-demos

Fix demos to accommodate new API changes.
Merge pull request #278 from cowlicks/move-utils

Move ipcluster, purge_cluster, and iopubwatcher to utils.
Merge pull request #281 from cowlicks/coveralls-omit

Omit coveralls checking the externals directory.
Merge branch 'master' into feature/even-more-examples-mkness