Pep8ify and add comment
Add failing test for sort and max_results
Enable variables to be prefixed with -

This is required to indicate a descending sort, e.g.

```
sort=["-foo"]
```

Needs to be passed to analytics as:

```
-ga:foo
```

This change assumes that variable names never start with a `-`.
Implement max_results and sort
Add failing test_long_query_max_results()
Implement fetching a limited number of rows

Before this commit, gapy would fetch as many rows as Google gives
`nextLink`s. Unfortunately, this breaks maxResults, since google returns
`nextLink` even if you tell it you only want 10 rows.

This change makes it so that nextLink is only followed if not enough
results have been fetched so far.
Fix: fixture only contains 2 rows
Add management.segments API call
Merge pull request #8 from frabcus/add-management-segments-call

Add management.segments API call
Merge pull request #6 from pwaller/add-max-results-sort

Add max_results and sort