Support directory traversal to find package root when loading and unloading
Update NEWS.md to reflect support for directory traversal to find package root
Use after_failure not on_failure

Travis documentation wants the key after_failure not on_failure:
http://docs.travis-ci.com/user/build-configuration/

This key has been updated at craigcitro/r-travis:
https://github.com/craigcitro/r-travis/blob/master/sample.travis.yml
Merge pull request #617 from lmullen/update-travis-template

Use after_failure not on_failure
Typo fix
Typo fix
Typo fix
Typo fix
Typo fix
Typo fix
Typo fix
Typo fix
Merge pull request #620 from bpbond/master

Fix documentation typos
check that path is character in package_root
Use is_root helper per @hadley
Test package loading
Use is_root helper in recursive traversal as well
revdep_check: return results invisibly
Don't update from Omegahat repo

The version of RCurl on Omegahat (1.96-0) causes segfaults on
R-devel.
Incorporate small changes per @hadley