Remove ideas for improvement (they're complete or near completion) and mention Flynn.
Pull the advanced installation sections into their own document
Update environment variable section to reflect new config plugin
Add upgrade instructions for users pre-27d4bc8c3c
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Merge pull request #303 from kkurian/patch-1

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dotcloud/docker#1869 is closed and released
Merge pull request #307 from mmalecki/patch-1

dotcloud/docker#1869 is closed and released