Add passChange form/templates; rework error msg.

Add:
	__init__.py
		-add route for passChange form.

	templates/passChange.html
		-page with passChange form for noscript visitors.

	templates/profile.html
		-add passwordChange form, which allows a logged-in user to
		change his/her password.

Ref:
	templates/layout.html, static/dynamic.js
		-group loginForm and passChangeForm into a credentialForm class,
		and identifying each with a unique id.

	templates/layout.html
		-condensed three similar error messages (to do with
		posting/viewing one's profile without logging in) into a generic
		catchall for code brevity.