Including Validate example

There's a similar example in the test file already
Updated example using Validate() to check the request
Fixed inconsistent indentation
Merge branch 'master' of github.com:superlogical/martini-contrib into superlogical-master
Added option for left & right delimiters

To prevent from “{{“, “}}” clashes between go’s template and
others(handlebars, angularjs also uses them).
fix code example

Code example references a direct call to `Error` which fails, proper example should us the `binding.Error` instead.
return `Content-Type: application/json` in `ErrorHandler

The `ErrorHandler` defaults to returning `text/plain` despite the fact that it actually returns JSON. I've set the `Content-Type` header to `application/json; charset=utf-8`.
Fix for the comment
Merge pull request #52 from danawoodman/patch-2

fix code example
Merge pull request #53 from danawoodman/patch-3

return `Content-Type: application/json` in `ErrorHandler
JMS #55: Added support for removing a session key

closes #55
Merge branch 'JMS-55'
Added a specific struct('Delims') to set template variable delimiters
Updated README with 'Delims' usage
Added test for 'Delims'
Merge branch 'master' of github.com:savruk/martini-contrib into savruk-master
Cleaned up Delims docs. Formatting
Changed Delim to Delims
Updated readme