#21 for email rule
#21 alpha and alpha_dash
#21 alpha_num
* refactors check() method
* if a key is not passed to the input object and there is a 'required' rule for it, it should fail
* adds more unit tests
* updates integer validation rule so that:

1. if input value is passed for a rule, it should return true. the required flag should be passed if you want it to fail if there is no value

2. it checks if the number has a typeof of number AND it only contains digits
* if value not supplied w/ alpha rule, it will pass. should use required rule if value must be present
* enforce values before checking in rules, otherwise returns true
if input for email is truthy, then run check. otherwise returns true
* make max rule not have an implicit required rule
only validate numeric flag if value is truthy
url has to be truthy in order to run check
size rule checks for truthy value before running validation.
adds another test to same rule
test cleanup
updates to validators to handle boolean values
* updated alpha rules to only check for strings, numbers, and undefined
* more tests for accepted validation rule
* accepted and alpha rules finalized
* refactor confirmed rule tests
* confirmed rule completed
* different rule refactored
* different rule complete
* refactored email and in tests
* in rule passes for undefined and empty string values
* email and "in" rules complete