Soledad close method checks if db exists.
Add messages to leap_asserts.
Change how tmp directoy is removed on Couch backend tests.
Fix sqlcipher test that was comparing wrong doc.
Add missing tests from TestRemoteSyncTargets.
Fix HTTP request bug.

Base64 encoding returned a \n at the end of the string and that was causing
trouble on the HTTP request when the token was added as an http header.
Monkey patch u1db to allow self-signed SSL cert