Save cache to output directory, not git repository.

This closes bug #2184326 on SourceForge. Some people may not have access to
their git repository, so we save the cache to the output directory instead
(which must always have write access anyway).

gitstats

 	
 	##
 	# Load cacheable data
-	def loadCache(self, dir):
-		cachefile = os.path.join(dir, '.git', 'gitstats.cache')
+	def loadCache(self, cachefile):
 		if not os.path.exists(cachefile):
 			return
 		print 'Loading cache...'
 	
 	##
 	# Save cacheable data
-	def saveCache(self, dir):
+	def saveCache(self, filename):
 		print 'Saving cache...'
-		f = open(os.path.join(dir, '.git', 'gitstats.cache'), 'w')
+		f = open(cachefile, 'w')
 		#pickle.dump(self.cache, f)
 		data = zlib.compress(pickle.dumps(self.cache))
 		f.write(data)
 
 os.chdir(gitpath)
 
+cachefile = os.path.join(outputpath, 'gitstats.cache')
+
 print 'Collecting data...'
 data = GitDataCollector()
-data.loadCache(gitpath)
+data.loadCache(cachefile)
 data.collect(gitpath)
 print 'Refining data...'
-data.saveCache(gitpath)
+data.saveCache(cachefile)
 data.refine()
 
 os.chdir(rundir)