(Bug 5212) Use LJ::Directories in LJ/ModuleLoader.pm.

LJ::ModuleLoader calls LJ::get_all_directories, which is defined in
LJ::Directories.  In normal site usage this isn't a problem, but in
other contexts it causes a compilation failure when the function is
not found.
(Bug 5212) Fix scoped variable warning in DW/Worker/ImportEraser.pm

This warning was causing t/00-compile.t to fail.
Merge pull request #514 from kareila/bug5212-perlcheck

(Bug 5212) Use LJ::Directories in LJ/ModuleLoader.pm.