enhance write_file with append mode, extend filetools unit tests
use read_file/write_file in toy_build unit tests to avoid occasionally failing tests due to garbage collection
use a local test install path rather than self.test_installpath purposely, to avoid garbage collection in Python 2.6 cleaning up the install path prematurely
no need for a local test installpath, remove generated modules after subtests
don't redefine self.test_buildpath and co in toy_build tests, use self.test_*path where it wasn't used yet
fix typo
include debug info for failing scripts test
Merge pull request #988 from boegel/fix_unstable_tests

Fix unstable tests