Fix font loading when adding scale (colorbar)

[peters77]

Add a check for font object in _add_scale as suggested by @djhoese

Now it should be possible to specify a font, fontsize and color for scale values/labels and colorbar title, e.g.:

'font': '/usr/share/fonts/truetype/dejavu/DejaVuSerif.ttf', 'font_size': 20,'line': 'white'

[coveralls]

Pull Request Test Coverage Report for Build 39

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.8%) to 44.965%

---

Files with Coverage Reduction	New Missed Lines	%
pydecorate/decorator_base.py	1	42.65%

Totals
Change from base Build 29:	0.8%
Covered Lines:	192
Relevant Lines:	427

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💛 - Coveralls

[codecov]

Codecov Report

Merging #14 into master will increase coverage by 0.83%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #14      +/-   ##
==========================================
+ Coverage   44.00%   44.83%   +0.83%     
==========================================
  Files           4        4              
  Lines         425      426       +1     
==========================================
+ Hits          187      191       +4     
+ Misses        238      235       -3     

Impacted Files	Coverage Δ
pydecorate/decorator_base.py	42.64% <100.00%> (+1.05%)	⬆️

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[djhoese]

Awesome! Thank you. Will make a new patch release since you were so quick to point this out.