Forward project directory to source services.

This helps to implement an efficient way to create source tarballs from Git repositories:
1. The cloned Git repository will be stored only once in a directory; all projects will use this repository (determined by the URL).
2. The bzip2 compressed tarball will be created via 'git archive $branch $filestoinclude --prefix=$name | bzip2 --best >$projdir/$name-$version'.
3. The version will be adapted automatically without the set_version service.
4. All branched/linked projects will be updated automatically (does not with current implementation).
5. Not to mention it saves space on source host(s).

osc/core.py

@@ -332,7 +332,7 @@ class Serviceinfo:
             name = call.split(None, 1)[0]
             if not os.path.exists("/usr/lib/obs/service/"+name):
                 raise oscerr.PackageNotInstalled("obs-service-"+name)
-            c = "/usr/lib/obs/service/" + call + " --outdir " + temp_dir
+            c = "/usr/lib/obs/service/" + call + " --outdir " + temp_dir + " --projdir" + os.path.abspath(os.curdir)
             if conf.config['verbose'] > 1 or verbose:
                 print "Run source service:", c
             r = subprocess.call(c, shell=True)