Support complete aggregation framework syntax
#1: parse ints in date()
Merge pull request #2 from alonho/agg

Add support for complete aggregation framework pipelines
Pass arguments to mongo aggregation functions in a list to overcome SERVER-9289
support None and null within find queries
update .gitignore
Partial fix for #4: add epoch support and parse dates with dateutil
Another solution for #4: replace 'in' with getitem to support defaultdicts for schema
add epoch_utc() parser