added prefix and suffix validators
added implementation and tests for substring validator
began adding implementation for predicate pased string matching
Merge branch 'master' into string-convenience
added wildcard matching methods to string validation
added proper error format for wildcard matching
renamed to TWTPatternExpressionStringValidator
updated to specify that the default case sensitivity is YES and updated to conform to style of approving validation if requirements aren't met
updated strings to conform to style
clean up documention
updated to use NSNotFound
updated 'matches' to 'has' and cleanup other stuff
updated tests per comments
renamed methods and forward declared them because 1992
renamed methods to remove 'string' suffix
Merge pull request #22 from twotoasters/string-convenience

String Convenience