Prevent subroutine prototype mismatch between Dancer's load and Module::Load

Without preventing Dancer's load subroutine form being exported it will conflict with Module::Load's load subroutine.  Giving warnings like:

Subroutine Dancer::Plugin::Email::load redefined at /usr/local/lib/perl5/site_perl/5.18.2/Module/Load.pm line 30.
Prototype mismatch: sub Dancer::Plugin::Email::load: none vs (*;@) at /usr/local/lib/perl5/site_perl/5.18.2/Module/Load.pm line 30.

This patch prevent's Dancer's load keyword from being exported.