[#13][s]: replace get_resource_length function with one-liner - fixes #13.
[#4,vendor][s]: forgot to add the openpyxl lib to vendor in 8c3641d890b0d5f038582ee2ab7206e4c42efd58.
[vendor/messytables][xs]: latest messytables with fix for use tempfile.mkstemp (use of which was breaking GAE).
[app.py][s]: fix (and test) for handling decimal types in json encoding.
[vendor/messytables][s]: pull down latest messytables with essential xls handling fix (no longer use tempfile).