Move Bucket class to TokenBucket

Better reflects the actual operation of the bucket. See
http://en.wikipedia.org/wiki/Token_bucket
Initial test framework, initial tests for TokenBucket
Change separator used in mark syntax
Default FileStorage location to configured tmp dir
Remove file viability test from FileStorage path construction
Working TokenBucket with underlying FileStorage

Also includes a cli-based driver to demonstrate basic functionality. Found at
examples/token-bucket.php
Remove unnecessary setting of last timestamp on constructor

Closes #2 - Functional TokenBucket Object
Merge pull request #5 from danapplegate/0.9-build

0.9 build