Doesn't work on Ubuntu 15.04

[owais]

On ubuntu 15.04, ipad_charge does not work and spits the following output to console.

ipad_charge: unable to claim interface: error -5
ipad_charge: error setting charge mode
ipad_charge: no such device or an error occured

[pmadhyastha]

You typically get this error message when the user does not have the necessary USB access permission.

Check the user permissions carefully.

[nitsanw]

@owais please try the PR and report back, might resolve your issue

[owais]

Sorry, I don't have an iPad anymore and I'm running OS X now :)

Thanks