Add license references and update attributions

[codecov[bot]]

Codecov Report

Merging #16 into master will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #16   +/-   ##
=========================================
  Coverage     96.39%   96.39%           
  Complexity      164      164           
=========================================
  Files            12       12           
  Lines          1527     1527           
  Branches         73       73           
=========================================
  Hits           1472     1472           
  Misses           36       36           
  Partials         19       19

Impacted Files	Coverage Δ	Complexity Δ
...a/cafe/cryptography/curve25519/UnpackedScalar.java	97.16% <ø> (ø)	15 <0> (ø)	:arrow_down:
...n/java/cafe/cryptography/curve25519/Constants.java	88.88% <ø> (ø)	1 <0> (ø)	:arrow_down:
...a/cafe/cryptography/curve25519/CompletedPoint.java	100% <ø> (ø)	3 <0> (ø)	:arrow_down:
...ava/cafe/cryptography/curve25519/EdwardsPoint.java	87.85% <ø> (ø)	35 <0> (ø)	:arrow_down:
.../cafe/cryptography/curve25519/ProjectivePoint.java	100% <ø> (ø)	3 <0> (ø)	:arrow_down:
...in/java/cafe/cryptography/subtle/ConstantTime.java	92.85% <ø> (ø)	7 <0> (ø)	:arrow_down:
...fe/cryptography/curve25519/CompressedEdwardsY.java	73.33% <ø> (ø)	7 <0> (ø)	:arrow_down:
...cryptography/curve25519/EdwardsBasepointTable.java	100% <ø> (ø)	5 <0> (ø)	:arrow_down:
...ava/cafe/cryptography/curve25519/FieldElement.java	97.88% <ø> (ø)	39 <0> (ø)	:arrow_down:
...cafe/cryptography/curve25519/AffineNielsPoint.java	89.47% <ø> (ø)	8 <0> (ø)	:arrow_down:
... and 2 more

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