Jira8 set deleted as unnecessary (atlassian-api#490)

* Added parameter for user() method:
 - get user by key

Now you need to use only named parameters.
For example, user(username='john') or user(key='john.d').
You can use only one parameter: username or key.

* Jira8 set deleted as unnecessary. All improvements will implementing in just Jira set.

Author: SLRover

atlassian/__init__.py

@@ -4,7 +4,6 @@
 from .confluence import Confluence
 from .crowd import Crowd
 from .jira import Jira
-from .jira8 import Jira8
 from .marketplace import MarketPlace
 from .portfolio import Portfolio
 from .service_desk import ServiceDesk
@@ -18,6 +17,5 @@
     'Stash',
     'Crowd',
     'ServiceDesk',
-    'MarketPlace',
-    'Jira8'
+    'MarketPlace'
 ]