Merge features from my augeas lexer

About a year ago (I guess about the same time as you), I wrote a Pygments lexer for Augeas for the [Augeas book](https://github.com/raphink/Augeas-book/tree/master/augeas-lexer).

I just saw you made one, too, so I've thought it better to send you my code and merge the two projects.

This PR adds a few lexers:

* AugtoolShellLexer parses augtool shell output;
* AugtoolLexer parses augtool code (without a shell prompt and shell output);
* PuppetAugeasLexer parses puppet code using the augeas provider;

Real life example: http://r.pinson.free.fr/augeas/augeas-book_colored.pdf