reshuffled the handbook

Referenced Page: 
Aegir Handbook

I have moved pages around in the handbook to remove what seemed to me an arbitrary distinction between "documentation" and "developping for aegir". So it flattens the tree a little, but shows important pages (installing aegir, getting help, using aegir) earlier in the tree.

Oh and I grouped a bunch of pages under "getting help".

The handbook is great, congratulations to Miguel for the hard work!

PS: I have finally created myself an account here. First: wow, user 78!! Second: gee, how did I take so long! ;)