Make relative URLs absolute inside src and href attributes

[majelbstoat]

Hello @majelbstoat, @kylehg,

Please review the following commits I made in branch 'jamie-relative-images'.

57181712a9526aff8720aeb22350fd9f85ad8d85 (2015-10-03 16:32:48 -0700) Make relative URLs absolute inside src and href attributes

R=@majelbstoat R=@kylehg

MANUAL TESTING=bunch of testing of relative and absolute urls

Code review reminders. By giving a LGTM you attest that:

• Commits are adequately tested
• Code is easy to understand and conforms to our style guides
• Incomplete code is marked with TODOs
• Logging and metrics are suitable

[majelbstoat]

YOLOMerging PHP.