Update license, config and docs.

[JimBobSquarePants]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

• Update License and headers
• Update Readme
• Update ticket template

[codecov]

Codecov Report

Merging #53 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #53   +/-   ##
=======================================
  Coverage   66.35%   66.35%           
=======================================
  Files          77       77           
  Lines        5071     5071           
  Branches     1071     1071           
=======================================
  Hits         3365     3365           
  Misses       1472     1472           
  Partials      234      234           

Flag	Coverage Δ
#unittests	66.35% <ø> (ø)

Impacted Files	Coverage Δ
...ing/Common/Extensions/GraphicsOptionsExtensions.cs	100.00% <ø> (ø)
src/ImageSharp.Drawing/Primitives/ShapePath.cs	100.00% <ø> (ø)
src/ImageSharp.Drawing/Primitives/ShapeRegion.cs	100.00% <ø> (ø)
...c/ImageSharp.Drawing/Processing/BrushApplicator.cs	84.37% <ø> (ø)
src/ImageSharp.Drawing/Processing/Brushes.cs	100.00% <ø> (ø)
src/ImageSharp.Drawing/Processing/ColorStop.cs	100.00% <ø> (ø)
...rc/ImageSharp.Drawing/Processing/DrawingHelpers.cs	100.00% <ø> (ø)
...eSharp.Drawing/Processing/EllipticGradientBrush.cs	100.00% <ø> (ø)
...p.Drawing/Processing/Extensions/ClearExtensions.cs	100.00% <ø> (ø)
...awing/Processing/Extensions/ClearPathExtensions.cs	100.00% <ø> (ø)
... and 66 more

---

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[tocsoft]

@JimBobSquarePants Probably best to make the change to 'Fonts' before this one. Then you can also update the dependencies in the same PR so the new release is dependent on only apache licensed components.

[JimBobSquarePants]

Haha yes, did them in the wrong order! Glad I took a moment for review.

[JimBobSquarePants]

@tocsoft Updated the reference now.