Previously git review could not properly query Gerrit servers via http
if the root of the Gerrit api was below /. This is because it was always
rooting the changes query api at /changes instead of /foo/changes if
hosted at /foo.
To fix this we read the project name from the config so that we can
remove the project name suffix from the urls then append changes/ to the
resulting url to get a properly rooted query url.
Note this was never a problem with ssh because ssh can't be hosted as
some subpath. Everything is rooted with ssh and gerrit.
Change-Id: I46e21dfdbbb7f60aa89a7b028501c0d953ae1d7f
f918bf76d2