Merge pull request #1660 from swryan/gui

gui - add support for expressions in connection frame
Merge pull request #1661 from swryan/gui

remove _repr_svg from Assembly, plt fails headless
Merge pull request #1662 from swryan/gui

gui - use xvfb for linux testing only, clean up unused js & MPL import issues
Updated python "go" script for new Sphinx version 1.2.2 (many bug fixes).
Merge pull request #1663 from pziegfeld/test_sphinx122

Updated Sphinx version to V1.2.2 (many bug fixes).
Uniform doegenerator needed to re-start its counter each time __iter__ is called
Update README.txt
Fixed uniform doegenerator so it handles nested loops
Merge pull request #1664 from hschilling/P66558096-uniform-doegenerator-restart

Uniform doegenerator needed to re-start its counter each time __iter__ is called
fixed a vtree copy bug that was caused by a traits issue (after a deepcopy, some things in the __dict__ were not showing up in _alltraits()
oops, had actual fix commented out in order to make sure the test failed
removed derivative output being written to stdout during openmdao test
Merge pull request #1665 from naylor-b/traits_bug

traits issue was causing the copy of a vartree not to work.  Also removed some unwanted derivative output during openmdao test.