Replaced a call to CaptureSVNStatus with a SCMWrapper::status

gclient: store gclient_entries as a dict

Currently we only store the relative path for entries.
We need to also store the url so that learn the repo type: git or snv.

Review URL: http://codereview.chromium.org/248011

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@27370 0039d316-1c4b-4281-b951-d872f2087c98