Remove unused code.

[jamesbyars]

The call to get the File object is not used in startCamera(), also getCameraFile() is taking care of getting the File, no need to make the same call in startCamera()

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[jamesbyars]

I signed it.

[googlebot]

CLAs look good, thanks!

[jamesbyars]

Build failure appears to be related to an environment variable setting used by Travis-ci. I see in the docs that the build should use the GOOGLE_APPLICATION_CREDENTIALS environment variable.

Here is the failure from Travis-ci:
Error: Received unexpected error "google: error getting credentials using GOOGLE_APPLICATION_CREDENTIALS environment variable: unexpected end of JSON input"

Related to #50

[jerjou]

Thanks!