Add FreeApplicative.analyze

[smungee]

In trying to port the FreeApplicative example from @jdegoes's ScalaWorld
2015 talk[1] to cats, I found that cats does not have a
FreeApplicative.analyze method, which allows us to compile a
FreeApplicative into a monoid.

This commit adds FreeApplicative.analyze, as well as a new test for
this, as per a discussion on gitter [2].

[1] https://github.com/jdegoes/scalaworld-2015/blob/master/src/main/scala/asmfree.scala#L32
[2] https://gitter.im/non/cats?at=561ed5373a0d354869528194

[codecov-io]

Current coverage is 75.71%

Merging #572 into master will increase coverage by +0.03% as of 6e2c3d5

@@            master    #572   diff @@
======================================
  Files          157     157       
  Stmts         2163    2166     +3
  Branches        68      68       
  Methods          0       0       
======================================
+ Hit           1637    1640     +3
  Partial          0       0       
  Missed         526     526       

Review entire Coverage Diff as of 6e2c3d5

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[adelbertc]

👍

[non]

👍

[non]

Thanks!