use the new AnyTableSet class in messytables for determining the file format, and removed all of the file format guessing code from here, and now that messytables supports looking inside of zip files allow zip files to be used with the datastorer
call the new messytables headers_make_unique function to ensure that we are passing postgres column headers that are unique within its length limit for column headers
improve logging of errors by actually outputting errors (s/info/error/) and only outputting the 'error' field in the JSON response
still must issue a datastore_delete otherwise a second call to update a dataset (e.g. if the dataset change upstream) would just append to the existing datastore table
better exception handling around deleting existing dataset
Merge remote-tracking branch 'tauberer/master'

Conflicts:
	ckanext/datastorer/tasks.py
Revert "Let requests build the request parameters"

This reverts commit a2e1c8a651717ae2ec7696ccd89b9d8ff768dfe7.