tcadr 0.3.0

This release:

• Corrects a bug where some data types showed as nonsensical numbers (e0cf0e3)
• read_tcad will always return a data_frame, instead of this being merely the default option. (de9c2f5)
• Removes the read_assignment function that was causing problems and that may have limited utility (ebc0647)
• Introduced continuous integration through travis-ci