Merge pull request #29 from mooballit/master

Do not convert the response to Unicode in case of PDFs
Add support for manual journals
Merge pull request #39 from russss/master

Add support for manual journals
Add filter support for order, offset, and page
Merge pull request #40 from gavinhodge/urlparams

Add filter support for order, offset, and page.
Add some more examples to the README and fix up some formatting issues.
Assume all strings are unicode.
Remove excess whitespace
Add support for Foo__isnull=True/False. Also, clean up our generate_param and get_filter_params to only use locally scoped variables for code clarity.
Ensure that filter always returns a set of results, even if only a single result is returned from the API. This brings pyxero inline with the Django ORM.
Leave the undecorated method behind and available via an underscore (e.g. _filter).
Ensure that now with the XML being parsed correctly, we return a single instance for Manager.get, and update tests accordingly.
Merge in pull request #41 from @gavinhodge (https://github.com/freakboy3742/pyxero/pull/41)
Fix incorrect constant used after PartnerCredentials patch.
Attachments upload support
README formatting tweak
Fix attachments example
Fix another error in attachments example
Generic algorithm for GUID detection
Add BankTransactions and BankTransfers