urlUtils should only strip path segments ending with colons IF the segment does not exist in the original URL.

[jeffbcross]

This issue is an enhancement to a bug fix I recently submitted, which @tbosch and I have discussed further and decided needs enhancement.

The urlResolve method will automatically strip the first segment of a path if the segment ends in a colon. This was to correct undesired behavior in the $location service using the file protocol on windows in multiple browsers (see #4680).

However, there could be cases where users intentionally have first path segments that end in a colon (although this conflicts with section 3.3 of rfc3986).

A simple solution to this problem is to add a check to make sure the first path segment of the input url does not end with a colon, to make sure we're removing an unintentional path segment.