Password reset_password, confirm_reset_password and complete_reset_password screens.

* Add a placeholders for password reset flow in FxA Client wrapper.
* Add a new file "url.js" which contains "searchParam"
* Move several common functions to base.js (isElementValid, displayError)

issue #121
Add XSS protection for redirectTo

* Add unit tests for Url
add a footer
Merge branch 'issue-121-password-reset-screens' of github.com:mozilla/fxa-content-server into shane-pwreset