Use PluginRemover to implement '-remove'

Previously this module implemented the '-remove' option by wrapping
itself inside a "Filter" bundle inside a second copy of itself. Now it
just uses the Dist::Zilla::Role::PluginBundle::PluginRemover role
instead.
Add test that specifies all possible options
Add Config::Slicer role
Declare test plan in advance
v0.142221

    - Switch to PluginRemover for implementation of "-remove" option
    - Add the Config::Slicer role to enable arbitrary plugin options
    - Improved tests, including tests for the two above additions