Lightbeam landing page

Addressing bug 926629. Initial version of landing pages for Lightbeam launch. Our goal is to have this go live on Sat Oct 26th. Please let us know if there are any changes we have to make and we will get to it as soon as possible.
Apply changes according to the suggestions mentioned in https://github.com/mozilla/bedrock/pull/1321.  This does not include fixes for reponsive design.
Apply changes according to the suggestions mentioned in https://github.com/mozilla/bedrock/pull/1321.  This does not include fixes for reponsive design.