Add support for Poisson injector. Allows randomized load profiles.

Refactored PoissonInjector to use scanLeft

Switched to fixed-time variable-user model, using Lewis and Shedler's algorithm
Document PoissonInjection usage
Upgrade AHC 1.9.0-BETA1, close #1982
Rename param into formParam, close #2003
Merge pull request #1990 from jamespic/poisson2

Core: Add support for Poisson injector. Allows randomized load profiles.
Don't highlight plain text as scala code
Merge pull request #2004 from notdryft/sphinx-highlight

Don't highlight plain text as scala code
Freshened layout
Merge pull request #2007 from notdryft/sphinx-layout

Freshened layout
Add Guillaume Corré as developer
Collapsible header
Merge pull request #2008 from notdryft/sphinx-layout

Collapsible header
Refine header
Merge pull request #2009 from notdryft/sphinx-layout

Refine header
Change pool key so because of the way AHC honors https pooling parameter
Upgrade Jackson 2.4.1.2
Fix old occurrences of param that had to be renamed into formParam
Documented Sitemap feeder. Resolves #1994
Add an option to prefer Jackson over Boon, close #2015
Append to #2015