Fixed local variable deprecation warnings
Fixed local variable deprecation warnings

Before this patch local variables that appeared in the
mongod.conf.erb template were not prefixed with an '@'. This
style is deprecated and produces warnings. This commit fixes
those warnings.

mmalchuk/puppetlabs-mongodb,parship/puppetlabs-mongodb,discovery-digital/puppetlabs-mongodb,discovery-digital/puppetlabs-mongodb,noris-network/puppetlabs-mongodb,parship/puppetlabs-mongodb,noris-network/puppetlabs-mongodb,mmalchuk/puppetlabs-mongodb,discovery-digital/puppetlabs-mongodb,fatmcgav/puppetlabs-mongodb,ResignationMedia/puppetlabs-mongodb,fatmcgav/puppetlabs-mongodb,mmalchuk/puppetlabs-mongodb,SanderSander/puppetlabs-mongodb,ResignationMedia/puppetlabs-mongodb,SanderSander/puppetlabs-mongodb,discovery-digital/puppetlabs-mongodb,ResignationMedia/puppetlabs-mongodb,SanderSander/puppetlabs-mongodb,noris-network/puppetlabs-mongodb,fatmcgav/puppetlabs-mongodb,parship/puppetlabs-mongodb