Merge pull request #1 from dre1080/initial

Applying golint suggestions
Removes unneeded parameter
Examples now require userID for access to a protected page
Fixes spelling and punctuation errors
Replaces Csrf with CSRF
Removes api key check and cleans up if GET statement
Merge remote-tracking branch 'upstream/initial' into initial

* upstream/initial:
  Removes api key check and cleans up if GET statement
  Replaces Csrf with CSRF
  Fixes spelling and punctuation errors
  Examples now require userID for access to a protected page
  Removes unneeded parameter

Conflicts:
	README.md
	csrf.go
Adding custom error option.

Adds a custom error response function to be set in csrf.Options.
It is called when CSRF token validation fails and defaults to a function which replies with a `http.BadRequest` error with message: "Invalid csrf token".