Split out ApplicationManagement and related sections

Split ApplicationManagement interface and other parts of the Runtime spec relevant to privileged applications only into their own spec, see:

http://anssiko.github.io/runtime/index.html
http://anssiko.github.io/runtime/privileged.html

See also:

http://lists.w3.org/Archives/Public/public-sysapps/2013Jun/0005.html

Given there are relatively many commits in this PR, here's a short summary to ease the review:

The first 11 commits in this PR ("remove X section") are about taking index.html as a starting point for privileged.html and removing all sections that are *not* specific to privileged applications (there's a typo in the first commit message, should be "use index.html as a starting point for privileged.html").

The remaining commits sans the last one are non-normative changes to make the extension spec (privileged.html) a valid stand-alone spec.

The last commit is about removing sections that were split into the extensions spec (privileged.html) from index.html.