Added test to catch NoneType error on refresh, fixed offending code

[fronzbot]

Description:

Adds exception catch to prevent NoneType error on refresh, added test to check behavior as well

• Unrelated: had to add two force methods to refresh for testing purposes. Should not change normal usage.

Related issue (if applicable): fixes #392

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 #401 (92a2cc2) into dev (0842739) will increase coverage by 1.56%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##              dev     #401      +/-   ##
==========================================
+ Coverage   84.32%   85.89%   +1.56%     
==========================================
  Files           8        8              
  Lines         957      957              
==========================================
+ Hits          807      822      +15     
+ Misses        150      135      -15     

Flag	Coverage Δ
unittests	85.89% <83.33%> (+1.56%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
blinkpy/sync_module.py	91.83% <50.00%> (+5.10%)	⬆️
blinkpy/blinkpy.py	80.54% <100.00%> (+1.35%)	⬆️
blinkpy/api.py	65.59% <0.00%> (+2.15%)	⬆️

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