Raise ArgumentErrors in Math.fibs
Raise ArgumentErrors in Integer#factors
Don't use should when testing for ArgumentErrors
Remove support for list comprehensions (it's confusing at not very necessary)
Merge branch 'develop' into feature/raise-errors
Raise exceptions instead of returning nils and doing other weird stuff (fix #23)
Raise exceptions when Arrays contain non-Numeric objects (fix #25)
Merge branch 'develop' into feature/raise-errors

Conflicts:
	spec/math_spec.rb
Bring Array#numerics back

It's useful for preparing Arrays to work with methods that require Arrays of
Numerics.
Merge branch 'feature/raise-errors' into develop
Update copyright year
Update docs to mention the new exceptions (fix #26)
Fix some improperly indented doc comments
In the docs, specify when a method can also return nil (besides its usual types)
Use Yard's @raise tag to document exception raises
Use Yard's @see tag when appropriate
Finish tests for Random (fix #27)
Fix Random#boolean and Random#coin to always use the correct random generator
Fix tests for Random so they don't depend on a certain random generator system
Change the Travis config to test on all branches