Correct datetime invocation
Catch more exceptions
Fix indentation error in "return"
Add a parser option to ignore resources

Some resources will always fail and will need to be ignored
by the script. Add an option to take resource id
as input and ignore the resources specified
Merge pull request #30 from okfn/prod-updates

Create an option to ignore resources
Add xlsx mime type to DATA_FORMATS
Fail gracefully if there is no resource to ignore

* Check if the self.options.ignore array is non-empty.
* Match again the resource['id'].
* Fix a small pep8 violation.
Merge remote-tracking branch 'upstream/master'