Add a first, hacky version of chrome app

Add a first, hacky attempt at a chrome-app that can communicate with the
mooltipass device over USB.
Read the correcct number of bytes

The MP device sends 64 bytes with each reply, not 65. Also, the command should
be in the second byte of the package, not the third.
Remove disused code
Merge pull request #50 from abbeman/master

Add a first, hacky try at a chrome-app