Create a debugging-version of /collect

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Name of related component: Measurement Protocol

Request summary:
It would be really nice to have a "testing"-endpoint that returns some kind of 
hint which parameters were accepted and which were not.
It could be a simple json that contains all the key=>value-pairs that were 
accepted and/or error messages for not accepted parameters of missing required 
parameters.

E.g.:
when I hit /testCollect with datastring:
tid=UA-123456-1&cid=5555&t=pageview&dp=%2FpageA
The repsonse could be: {error:"Version is missing"}

or I hit /testCollect with datastring:
v=1&tid=UA-123456-1&cid=5555&t=pageview&dp=%2FpageA&foo=bar
The response could be: {error: "foo is not a valid parameter"}

....

Use Cases:
Debugging, if e.g. a custom dimension doesn't go through. Now I need to wait 
till the next day to see if Analytics accepted my custom dimension.

Original issue reported on code.google.com by fab...@gmail.com on 17 Jun 2013 at 12:47

AbdFatah / analytics-issues

Create a debugging-version of /collect #308