Fix extremely embarrassing bug thanks to @doomrobo

Bug causes sfs to upload a the filename as the image data. The problem
is that we're supplying filename as an argument to the method that does
the uploading -- but the argument should be the image data.

This commit will fix this issue by changing having the upload function
do the data reading.
Merge pull request #3 from doomrobo/master

Login errors are handled (and not saved) and can now upload file contents (not just filenames)
Handle relative paths correctly
Update comments in API file
Add @doomrobo to authors
added requirements.txt for pip
updated README install instructions
Update README
Merge pull request #6 from anshukla/master

Add requirements.txt for all dependencies
Update LICENSE to have Chad's name (derp derp derp)
Add @anshukla to README authors section
Merge branch 'master' of github.com:hausdorff/snapchat-fs
Merged with upstream 4a8ad30bf8c0f1b7288d2796ef30267beaf0a86f