Add tuner bandwidth support

[nocarryr]

Adds ability to set tuner bandwidth on supported devices.

Uses the rtlsdr_set_and_get_tuner_bandwidth in the librtlsdr development branch librtlsdr stable branch if available to return the bandwidth that was actually applied.

• Reference to librtlsdr api
• librtlsdr pull request that added the functionality

• Integrate with rtlsdrtcp
• Add tests

[coveralls]

Coverage decreased (-1.6%) to 84.479% when pulling 3518f91 on nocarryr:nocarryr-patch-2 into 3479723 on roger-:master.

[nocarryr]

See #50

[coveralls]

Coverage decreased (-1.1%) to 84.941% when pulling 10e7458 on nocarryr:nocarryr-patch-2 into 3479723 on roger-:master.

[coveralls]

Coverage increased (+0.1%) to 86.471% when pulling b22869b on nocarryr:nocarryr-patch-2 into 91a9119 on roger-:master.

[coveralls]

Coverage increased (+0.1%) to 86.471% when pulling 87106ee on nocarryr:nocarryr-patch-2 into 91a9119 on roger-:master.

[nocarryr]

@roger- I think this ready to be merged. Do you think it should be a squash merge given the number of commits?

Edit:
On second thought, I really don't like the way squash merges look:
91a9119
That was the merge commit for #52 and I think it is less useful than having the actual commit history. That's just me though.