Add arm property to camera, deprecate motion enable method

[fronzbot]

Breaking Change:

The BlinkCamera.set_motion_detect() method is deprecated and being replaced with BlinkCamera.arm. Usage is as follows:

To arm/disarm a BlinkCamera object named camera, just set the arm property to either True or False like so:

camera.arm = True

Calling the same property will return the last updated camera status (perform a refresh at the sync module or blink level to update the status after setting).

Checklist:

• Local tests with tox run successfully PR cannot be meged unless tests pass
• Changes tested locally to ensure platform still works as intended
• Tests added to verify new code works

[codecov]

Codecov Report

Merging #273 into dev will decrease coverage by 0.18%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##              dev     #273      +/-   ##
==========================================
- Coverage   82.36%   82.17%   -0.19%     
==========================================
  Files           8        8              
  Lines         771      780       +9     
==========================================
+ Hits          635      641       +6     
- Misses        136      139       +3     

Flag	Coverage Δ
#unittests	82.17% <66.66%> (-0.19%)	⬇️

Impacted Files	Coverage Δ
blinkpy/camera.py	82.75% <66.66%> (-1.36%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6a5256e...cc860c3. Read the comment docs.