fix(client): Fix form validation on browsers that do not have HTML5 form field validation.

* IE < 10 do not have native form field validation. Validation must be done manually.
* To form.js, added validatePassword and validateInput.
* validatePassword validates passwords
* validateInput only checks if an input field is required on browsers without HTML5 validation. On other browsers, HTML5 validation will take effect.

fixes #1113
fixes #185
Merge pull request #1131 from mozilla/issue-1113-form-validation

fix(client): Fix form validation on browsers that do not have HTML5 form...