README cleanup

Not sure if the line "Make sure you've created CLs with any imported GH changes." under Troubleshooting needs to stay or not.
Link mistake
Markup fixes so there are no parsing errors.
Add doctype to preview template

Adding <!DOCTYPE html> because I was getting the browser user agent styles applied instead of the DCC styles over in /multidevice.

StackOverflow: http://stackoverflow.com/questions/11348727/why-does-user-agent-stylesheet-override-my-styles

Who knows what other formatting issues it may be causing.
Merge pull request #115 from pearlchen/preview-template-fix

Add doctype to preview template
Merge pull request #114 from pearlchen/patch-1

README cleanup
Merge pull request #113 from Garbee/emulation

Markup fixes so there are no parsing errors.
Merge pull request #112 from WellingGuzman/patch-1

Link mistake
protocol link