Fix test-mode

When running as non-root, mongrel2 attempts to run in a test-mode.
Some recent enhancements to the chroot and daemonize code broke that.
Update links to tarball for 1.9.0
Bump version number
Merge branch 'release/v1.9.1' into develop
Delete gcov files more selectively.

Previously, make target 'clean' would delete all '*.gc*' files, this would
erroneously delete 'src/polarssl/tests/suites/test_suite_cipher.gcm.data'.

This contributed to marking the src/polarssl submodule dirty and caused
polarssl's test suite to fail.

Now it deletes only '*.gcno' and '*.gcda' files.
Merge pull request #216 from cpick/delgcov

Delete gcov files more selectively.
Merge remote-tracking branch 'upstream/develop' into develop
Merge branch 'develop' of github.com:fanout/mongrel2 into develop