"using salt at scale" tutorial for the docs
url test
url test2
link test2
added links to two auth-loop issues
put infos into a note box
highlight topics
remove all you's and rewrite some sentences
remove all you's and rewrite some sentences
Merge branch 'salt_at_scale_doc' of https://github.com/felskrone/salt into salt_at_scale_doc

Conflicts:
	doc/topics/tutorials/intro_scale.rst
fix link
rewrite a few sentences, re-ordering, etc.
Merge remote-tracking branch 'upstream/develop' into develop
Merge remote-tracking branch 'upstream/develop' into develop
add master_sign_key_name and generation of the actual sign-key-files if activated
make MasterKeys() more flexible by allowing different key-names.

MasterKeys() should be able to handle more than one hardcoded key.
The default is still to just handle master.* files but can also generate
new key-pairs with different names and return the pub-key.
fix join()'s to form the correct file names
add key name to logging output
add settings for master and minion to sign the public / verify pubkey signature

Add a setting for the master to generate a new signing key-pair for signing purposes
and use the key-pair to sign the masters public key that is send to authenticated
minions.

Add a setting for the minion to verify the signature of a public key received from
the master. Requires to have the signing key-pair from the master on the minion.
Add optional signing of the master pubkey if enabled in config.

Uses salt.crypt.sign_message() to create a signature of the pubkey
and adds that signature to the payload send to authenticated minions.