reorganize Readme

Moved paragraphs around so least technical (most user-oriented) is on top, then tech/contributing (hacker info) is near the end.  This allowed to streamline the prose, but I tried to avoid changing the text as much as possible.

Linked blog in welcome section (great for finding features; helps users decide if Brackets is for them).

Used H4 vs **bold** for sub-headers.
more terse, less repeated text

(note to self; don't Push with only 4 hours of sleep)
more terse, less repeated text, ordered helping steps
Moved live highlight
From file menu to view menu.
updated pt-br translation for a better readability.
reorganize getting help
Animate inline editors open.
Use Python syntax highlighting for .wsgi file extensions, ie. Python web apps using mod_wsgi.
clean up from review
Push update/remove management into ExtensionManager
Removes methods that simply delegate to ExtensionManager
Incomplete: pulling the update/remove action into the Dialog.

The tests have not yet matched the refactoring, but the idea is
to have the extension manager dialog trigger the update/remove
functionality, rather than the individual views.
Merge remote-tracking branch 'upstream/master' into livehighlight
Changed the name to live preview highlight
Find In Files on an untitled document should initiate a Find session in that document
Moved live preview highlight
Addresses review comments and detects updates.
Change synchronizeRegistries to synchronizeEntry for clarity
Code review fix
Properly sync gutter widths using CMv3 gutter API