API: some methods are using the wrong HTTP verb

[Kernald]

Some methods are currently POST methods, but should be GET:

• tags/all
• tasks/serial
• user/auth_gtg (by the way, auth_gtg is member of GTG API: the name should be auth only, as we know we're talking about GTG)

Should be DELETE:

• tasks/delete

Should be PUT:

• tasks/bulk_update

See here about HTTP verbs meanings: http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html

[parinporecha]

@Kernald - I've modified Task Update and Delete methods to PUT and DELETE respectively. The rest methods will be updated when the auth_token is implemented to replace username and password.
I've also updated all the URIs. Gathered them to one place in - api/ and modified some names. Please check the changes on the docs page.
I'll close this issue when the remaining methods which should be GET are changed to it

[Kernald]

While you're changing the API path, you should maybe add a version number, something like that: /api/v1/tags/all. This way, if one day you need to rewrite the API in a non-compatible way, you can let the previous one for a while, waiting for devs to migrate to the new one.