add save_to_file fuction, closes #42
add check for .spr extension in save_to_file function
implement support for image files to be converted to sprites, closes #41, needs testing on a raspberry pi
implement rotate and rotated functions, closes #43, needs to be tested on raspberry pi
fix small bugs
change checking filetype to use subprocess instead of magic library
fix image to sprite implementation
clean up some code and make comments, change default text size to small
Merge pull request #51 from scottsilverlabs/dev/jpsnyder/led/sprite

Dev/jpsnyder/led/sprite