get pandas to try and detect the date
remove convert_objects
add infer_datetime_format
avoiding reparsing file for each date column when calculating temporal

still have to parse the file twice though.
simply date detection
only use our custom parser when we know which columns are dates

Although pandas default one uses dateutil, it's wrapped with other code
so that it handles errors more gracefully.
temporal extent error handling
infer_schema_from_csv: better error checking
Merge branch 'master' of github.com:ckan/ckanext-b2 into date-type-autodetection

Conflicts:
	ckanext/datapackager/lib/csv_utils.py
	ckanext/datapackager/tests/lib/test_csv_util.py
Rename a couple of variables

Variableames buffer and type were overriding Python builtins
Delete an unnecessary # TODO comment
Merge branch 'date-type-autodetection'