Add Test::Spelling to test-recommends for travis-ci
Avoid running author tests for other modules in travis-ci.

Some testing modules we depend upon (such as Pod::Spell) have author tests which die
if their testing dependencies are not installed, rather than skipping. This results
in travis tests always failing.

We now set the appropriate testing flags only for our own test suite, not others.

This should also speed up travis run times.
AUTOMATED_TESTING and NONINTERACTIVE_TESTING set for entire install phase.
Merge branch 'master' into cache_improvements