Extend the default timeout for killing apps and allow it to be controlled via
  an environment variable.

DELTA=8  (6 added, 0 deleted, 2 changed)

git-svn-id: http://google-toolbox-for-mac.googlecode.com/svn/trunk@636 7dc7ac4e-7543-0410-b95c-c1676fc8e2a3