Microposts; session expiration; reorganize JS & CSS assets
	- Install the Annotate gem.
	- Move custom JS from application.js to topher_standard.js.
		Remove the listener to inhibit closing the navbar dropdown menu
		as it turns out this was unnecessary.
		Added a listener for updating char count when authoring posts.
	- Move custom CSS from application.csss to topher_standard.css.scss.
		Consolidate these styles slightly.
	- In general, simplify & streamline usage of Bootstrap classes.
	- Remove cruft from routes.rb. Restore /signout to the default request
		method :delete, rather than :get.

	- Add ApplicationController#refresh_session, with a before filter;
		this expires a login session after 1 hour inactivity.
	- Fix ApplicationController#require_signin to redirect the user to
		the current request URL (rather than the referrer) after login.
	- Some minor tweaks to the global navbar partial.
	- Form elements on /signin don't need an ID, if I'm using Capybara right.
	- Autofocus HTML5 attribute on signin and signup forms.

	- Migration: create table microposts.
	- A User has many microposts, and each micropost belongs to a user.
		Add user#feed.
	- Static#home loads the feed of microposts for the
		current user, and lists the posts on the page. Paginated.
		Set up a 2-column layout.
	- Users#show loads microposts written by the scoped user, paginated,
		and lists them on the profile page.
		Also, the user can write a new micropost from a form on their profile.
		Set up a 2-column layout.
	- Users#index displays the # of posts written by each user.

	- Rewrite & consolidate most spec files - I'm still feeling out my ideal
		testing style.
	- Wrote factory for microposts.
	- FactoryGirl calls no longer need to call the FactoryGirl class by name.
	- Modified spec helper visit_with to accept request parameters as a hash.
	- Modified spec helpers click_link_next/previous to verify that the link is
		active, before clicking it.