Add Steven Danna as a maintainer of Dev Tools

I've fixed a number of chef-shell and knife related bugs, written a
number of popular knife plugins that build on top of these systems,
and understand the related code well.
drop ruby 1.9.x support for Chef-12

Ruby 1.9.3 is in security-only maintenance phase which means that
bugs for the core ruby interpreter will not be fixed and Chef cannot
support ruby 1.9.x.  Users should be using omnibus-chef packages
which come with a built-in ruby 2.x or should upgrade their own
installations to ruby 2.x (and accept that ongoing upgrade and
support cost).  Chef 11 will continue to be shipped on ruby 1.9.x
until Chef 11 is EOL.
update docs for dropping support of 1.9.3
Remove 1.9 from travis, bump 2.1 to .5 patch release
Force TK to install prerelease Chef pkg for now

In the future (after Chef 12.0.0 is released) we should remove this. For
now, we need to force TK to install a prerelease version of the Chef
package, so it will include Ruby 2.1, and therefore not choke on
our requirement for Ruby >= 2.0
Remove 1.8 and 1.9 specific monkey patches
Ensure 'uri' is required where it's used.

URI previously was globally available because chef.rb loaded it via a
monkey patch for the URI class.
Merge pull request #2485 from opscode/ssd/maintainer-app

Add Steven Danna as a maintainer of Dev Tools
Adding myself to relevant component maintainer