Remove PHP 7 from Travis build
Remove PHP 7 from Travis build

We have the "Int" rule but "int" is reserved word in PHP 7, so, until we
rename this rule - which will be just on our first major release -, we
will have no support for this version of PHP.

mrsoto/Validation,regdos/Validation,Ye-Yong-Chi/Validation,Whyounes/Validation,thedavidmeister/Validation,jpjoao/Validation,Respect/Validation,rogeriopradoj/Validation,lalocespedes/Validation,riyan8250/Validation,rozehnal/Validation,guilhermesiani/Validation,hudolfhess/Validation,solvire/Validation,osiux/Validation,Respect/Validation,zinovyev/Validation