added sign cache size constants - default to 10 each
changed signCache from a HashMap to a ConcurrentLinkedQueue
added locationEquals() function to SignDAO
fixed a bunch of small glitches, everything seems to work well now

git-svn-id: http://pxncommon.googlecode.com/svn/trunk@39 f5fbd6b6-c213-558c-f92f-5ab434f62466