Esipy

Change :
* `EsiSecurity` object no longer require `app` object to be initialized to get SSO Urls (authorize, token).
* You can still use it, as before and your app will still work the same as before
* You can manually give a `sso_url` instead, to say whether you want SISI / TQ SSO (default is TQ) instead of the app object.
* If both are given, priority is set to the `app` object.
* Use of https://esi.tech.ccp.is/verify/ for verify instead of the sso endpoint (https://login.eveonline.com/oauth/verify)

This introduce a small breaking change if you init `EsiSecurity` without keyword, since `app` parameter is no longer the first parameter. You need to:
* either use keywords to init
* put `app` parameter in the 4th parameter [not recommended]

* Add RedisCache. This cache allows you to use EsiPy with a Redis backend. [14]
* Fix APIException definition [17]

Minor release to update the pyswagger version requirement as it prevents from having a bug with `number/int32` format

* Update pyswagger dependency (prevents bugs)

* Catch network issue by catching requests ConnectionError.

When this happens, the request will fail, and instead of raising an exception, it will simply enter the process like another error 500. When in retry process, the request will retry, just like any other request.

The error body will contain a json object,

{
'error': 'the http error message from the exception',
}


Thanks to Ebag333

* Adds retries on 5xx errors, up to 5 retry. Used when EsiClient is initialized with `retry_requests=True`
* Adds multiple request method with thread pool

Thanks to a-tal and antihax