Remove two copies of underscore.js from Meteor, using NPM package instead.

Follow-up to 27382c6. A step towards addressing issue #302.

We still have one copy in the underscore smart package, for serving to clients.
Fix increment-version script for bundled underscore
Adding expiresAt property to Google login data for accounts-google. fixes #525
Some minor modifications to 79405a495d4acaffc56042f8f7e15b5b34b6171f
Removed linkedin package from this PR

Login services should be defined from within their packages

Corresponding login service assets (images and css should be in their respective packages not inside of accounts-ui-unstyled)

Conflicts:
	packages/accounts-linkedin/linkedin_client.js
	packages/accounts-linkedin/package.js
	packages/accounts-ui-unstyled/login_buttons.js
	packages/accounts-ui-unstyled/login_buttons_images.css
Tests for the functionality we want
Accounts._loginButtons.getLoginServices returns unique services

This may be improved by passing an iterator to _.uniq instead of doing
this malarkey I did for the first run with JSON stringify and parse. ^_^
Add password to the available service buttons if it's included
Vastly simplify by removing the JSON parsing.

Instead, just run _.uniq on the Accounts._loginButtons.loginServices.
DUH. PRESTO!
Variable declarations on one line; self instead of that.
Remove uniqueness check. Devs shouldn't be idiots :)
Make sure password is last
Oops, we should memoize the last service in case we need to swap
Remove whitespace
Simplify and fix accounts-ui listing of login services
Rename css files in oauth login provider packages
Merge PR 572 into devel.
Encode ! and other special characters in params for Meteor.http.call and oauth1 methods
Add statusCode and data to OAuth1Binding call response error
Remove arguably unhelpful check