Cache: fixed py2.5 syntax error
SSLServer: Don't decode request content

This only exists in py2.7+, and only to expand gzipped request
content, which the Bcfg2 client doesn't support (and, given the py2.7
requirement, won't any time soon).
testsuite: removed obsolete can_skip variable

This was needed when we implemented skipping ourselves in a hackish
way; with unittest2, skipping is implemented correctly, so tests can
always be skipped
testsuite: Skip Probes DB tests if django is not available