Update Travis config
Fix refactoring error and eliminate code block that was silently broken
Don't hardcode python 2.7 in Makefile
Always line buffer sys.stderr wrapper
Revert "Don't hardcode python 2.7 in Makefile"

This reverts commit 983658c8113300a5bf8385abdc725d99d8422309.
Changelog and version updates for v0.100.0
Include new requirements spec files
Generalize requirements file include
Eliminate use of nosetests, which has i18n bugs
Use encoding from locale (it seems to be absent as a stream attribute sometimes)
Remove debug statements that trigger encoding errors
Clear the jq directory as part of make clean
Use byte literal when scanning for newlines
Travis: run a subset of tests

Hopefully this subset is fast and lets Travis complete builds quickly.
Do not hardcode Python 2.7 in Makefile
Deactivate Travis virtualenv before running tests

This avoids interference between the Travis virtualenv and our nested virtualenv when installing packages.
When running tests, install all dependencies' executables
Add Travis badge
Add link to Travis
Use err_exit in dx_build_app