Rfapi

- Use a request session to reuse tcp connections.

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- Due to Recorded Future API branding conventions, we are changing the names of our two customer facing APIs.
- The *ApiClient* will is now named *RawApiClient* and the *ApiV2Client* is now the *ConnectApiClient*.
- Imports of *ApiClient* and *ApiV2Client* will continue to work, but are deprecated.
- The files *apiv1client.py* and *apiv2client.py* have been renamed to *rawapiclient.py* and *connectapiclient.py* respectively.
- *QueryResponse* classes in *query.py* with ApiV2* names have been renamed, but will continue to work due to aliasing. These are *ApiV2Response* => *ConnectApiResponse*, *ApiV2FileResponse* => *ConnectApiResponse*, and *ApiV2CsvFileResponse* => *ConnectApiCsvFileResponse*.
- Test files have been renamed.
- Added functions to get demo events from the Connect API.

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- Introduces *ApiV2Client* to use with Recorded Future simplified APIv2, and refactors some code into a common parent *BaseApiClient* for both the *ApiClient* and *ApiV2Client*.
- Minor bug fixes

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- Fix exception message formatting bugs.
- Fix paging bug
- New classes *HttpError* and *AuthenticationError* that parses the server error
- Add support to not use gzip for transfer.

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- Add warning on incorrect limit when paging.
- New: class *InvalidRFQError* replaces *UnknownQueryTypeError*.
- Add feature to set *app_version* and *app_name* for tracking.
- Use headers only for paging.
- Some pep8 fixes.
- Minor bug fixes.

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- Add retry logic on read timeouts.
- Fix CSV paging.
- Add option to return *QueryResponse* objects when paging.