(#15193) Fix StaticCompiler#store_content

Without this patch the static compiler's store_content method improperly
calls the indirector in a way that produces fatal exceptions preventing
catalog compilation.

These errors take the form of:

NoMethodError: undefined method `find' for
Puppet::FileServing::Content:Class

This patch fixes the problem by sending the messages to the right
places for Puppet 2.7.x and Puppet 3.x