Summary:
Currently, mock routes can only be created for GET and POST HTTP method types. Mocks should support all the valid HTTP method types.
See specification for a list of valid types:
https://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
This was requested in issue: https://github.com/facebook/flipper/issues/1960
Here is a screen shot showing the new values added to the select list:

## Changelog
Network Plugin - support all valid HTTP method types in mock routes
Pull Request resolved: https://github.com/facebook/flipper/pull/1962
Test Plan:
Define mock routes using additional method types
Using "Flipper Messages" plugin, verify that new types have been sent to device
Reviewed By: passy
Differential Revision: D26635050
Pulled By: mweststrate
fbshipit-source-id: 6d85ac346bd18687516a3566d1048982ec7cae46