bumping plek to 1.0.0
Remove usage of Plek.current.environment

It has been removed in v1.0.0 and we need a different mechanism.
Different initializers will be provided at deployment time to set
the constant to a particular value.
Merge pull request #49 from alphagov/relax-plek-usage

Remove usage of Plek.current.environment
Merge pull request #48 from alphagov/bump-plek

bumping plek to 1.0.0