Added patterns to cover ISO8601 dates with miliseconds.

Currently it is impossible to query for dates with sub-second accuracy from cqlsh because the parser doesn't recognise dates formatted like `2013-09-30 22:19:06.591`. This pull request adds the following four ISO8601 patterns:
````
"yyyy-MM-dd HH:mm:ss.SSS",
"yyyy-MM-dd HH:mm:ss.SSSZ",
"yyyy-MM-dd'T'HH:mm:ss.SSS",
"yyyy-MM-dd'T'HH:mm:ss.SSSZ",
````
This change also allows the minTimeuuid/maxTimeuuid functions to take dates with milisecond granularity.