Extract path info from requests without decoding

Extract path info from requests without decoding

Gitiles malfunctions in conjunction with jgit and guice
because of a recent Guice bug fix. Work around the problem
by parsing the URI directly, bypassing the unescaping
performed by the getPathInfo method.

This rest of this message is copied from
https://gerrit-review.googlesource.com/#/c/60820/ :

The fix for Guice issue #745[1] causes getPathInfo() within the
GuiceFilter to return decoded values, eliminating the difference
between "foo/bar" and "foo%2Fbar". This is in spec with the servlet
standard, whose javadoc for getPathInfo[2] states that the return
value be "decoded by the web container".

Work around this by extracting the path part directly from the request
URI, which is unmodified by the container. This is copying the Guice
behavior prior to the bugfix.

[1] https://github.com/google/guice/issues/745
[2] http://docs.oracle.com/javaee/7/api/javax/servlet/http/HttpServletRequest.html#getPathInfo()

Change-Id: I7fdb291bda377dab6160599ee537962d5f60f1e8
Signed-off-by: David Pletcher <dpletcher@google.com>