Fixing wrong type of params option in yum_repository module (#2371)

This commit fixes incorrect type of the "params" option of the
"yum_repository" module. Without this fix the value of the "params"
option is read as a string instead of as a dictionary which makes
it impossible to define any additional YUM repository parameters.

lib/ansible/modules/extras/packaging/os/yum_repository.py

@@ -655,7 +655,7 @@ def main():
             mirrorlist=dict(),
             mirrorlist_expire=dict(),
             name=dict(required=True),
-            params=dict(),
+            params=dict(type='dict'),
             password=dict(no_log=True),
             priority=dict(),
             protect=dict(type='bool'),