refactoring, RoboHydra tests
RoboHydra tests, URL sanitizing

* RoboHydra tests
* intelligent URL sanitizing (fixes #58, fixes #49, see issue #11, should fix #45)
Always append trailing slash to address-book/calendar home set to avoid redirections
avoid NullPointerException (hint from ANR)
Importing calendar colors from <calendar:color xmlns="http://apple.com/ns/ical/"> element (see #31)
Version bump to 0.3.8 (version code 12)
Allows users to disable hostname verification (SSL)

Users of DavDroid may use their own servers, possibly with several virtual HTTPS hostnames.
To allow them to use DavDroid, this commit adds an option to disable hostname verification
for SSL handshake as there is no support for SNI in Apache DefaultHttpClient.