New release for Locator.locate_many_signed fix

Added #to_gid_param and #to_sgid_param as short-cuts for to_gid.to_pa…

…ram and to_sgid.to_param for convenience

Bump version for new feature

Release 0.3.0

* Rename model.gid -> model.to_gid so we don't collide with existing methods
  rails#36
* Customize gid locator per gid://appname
  rails#15
* Signed Global IDs now have expiry timestamps and a specific purpose
  rails#20
  rails#29

Release 0.2.3 with :verifier support

Bump for the parse fix

Bump version for the latest fixes and improvements