Update Gemfile to use gemspec
Write behavior for "custom_tlds" option
Add specced behavior for "custom_tlds"
Add spec for nested custom TLDs
Update README
Revert reference-style linking in README
Revert "Update Gemfile to use gemspec"

This reverts commit ac0135312201d4b2206089887e1f661480a6a036.
Version bump to 0.0.6