Remove needless reloading of each CachedCookbook on every resolve

For most actions, this turns an O(n^2) situation into O(n). Because
we're not needing to reload the cookbooks every time, Celluloid also
becomes unnecessary and we can remove that dependency, simplifying
a few more things.

Given a Berksfile containing all 107 cookbooks from the original
opscode repo (https://github.com/opscode/cookbooks/tree/0.10.rc.0)
and a warmup run to cache the cookbooks locally in ~/.berksfile, the
difference is striking:

Before fix (v2.0.9):

    ~/Code/berks-perf-test $ berks install
      ...
    ~/Code/berks-perf-test $ time berks install
      ...
    real  0m22.425s
    user  0m19.823s
    sys 0m3.673s

After fix (this commit):

    ~/Code/berks-perf-test $ berks install
      ...
    ~/Code/berks-perf-test $ time berks install
      ...
    real  0m3.527s
    user  0m2.892s
    sys 0m0.584s

Signed-off-by: Evan Owen <kainosnoema@gmail.com>
Remove the argument previously added for CachedCookbook#pretty_print

Since pretty_print is the interface for the stdlib PP class, there was
some confusion over what this method was for. The last commit wasn't
the place to fix it though, so removing for now.

Signed-off-by: Evan Owen <kainosnoema@gmail.com>
Use the more semantically correct #collect instead of #map

Signed-off-by: Evan Owen <kainosnoema@gmail.com>
Add Celluloid reset back to spec runs for Ridley

Since Celluloid is still a dependency of Ridley, it should still be
shutdown and booted before each test to ensure there are no orphaned
threads.

Acked-by: Jamie Winsor <jamie@vialstudios.com>
Signed-off-by: Evan Owen <kainosnoema@gmail.com>
Remove CachedCookbook::loaded to hide internal implementation

We're not using this getter yet, and the fact that cached cookbooks
are loaded and stored on the class doesn't need to be exposed (yet).

Acked-by: Jamie Winsor <jamie@vialstudios.com>
Signed-off-by: Evan Owen <kainosnoema@gmail.com>
Merge pull request #829 from CoTap/2-0-stable-resolve-perf

Avoid reloading each cached cookbook on every resolve