Fixes Executing Callbacks Multiple Times

Enter and exit callbacks were being executed multiple times during window
resize. I think this is because there is a delay before the class is
actually added to the element and that is what we are using to determine if
the breakpoint matches. Instead, we use breakpoint name as a data attribute
on the element and set it true or false.
Merge pull request #4 from reusables/fix_execute_callbacks_once

Fixes Executing Callbacks Multiple Times
Version bump
Merge pull request #5 from reusables/fix_execute_callbacks_once

Forgot Version Bump
Array.prototype.forEach not supported in IE8

I keep forgetting.
Merge pull request #6 from reusables/fix_forEach

Array.prototype.forEach not supported in IE8
Fix forEach fix.
Fix for loop in Breakpoints.evaluate.

Oy, I can't do anything right, can I?
Abort breakpoint evaluation early if nothing has changed.
Adds API Docs.
Adds examples
Version Bump
Merge pull request #8 from reusables/docs

Docs
Revise docs

+ Condense overloaded function docs.
+ Add section title for params.
Version Bump
Type hint define function for consistency
Merge pull request #9 from reusables/docs_revise

Revise Docs
Update Example in README.md