Update various modules for check_mode

This updates the following modules to support check_mode:
* apt_key
* apt_repository
* easy_install
* pip - will always report changed due to the way it handles state
* seboolean
* selinux
* slurp - since nothing changes, it just adds that it supports
  check_mode
* subversion - reports changed when checking out new repo and
  when updating.
* supervisorctl
* svr4pkg

See issue #2114.

library/svr4pkg

@@ -128,8 +128,9 @@ def main():
             state = dict(required = True, choices=['present', 'absent']),
             src = dict(default = None),
             proxy = dict(default = None)
-            )
-        )
+        ),
+        supports_check_mode=True
+    )
     state = module.params['state']
     name = module.params['name']
     src = module.params['src']
@@ -146,6 +147,8 @@ def main():
             module.fail_json(name=name,
                              msg="src is required when state=present")
         if not package_installed(module, name):
+            if module.check_mode:
+                module.exit_json(changed=True)
             (rc, out, err) = package_install(module, name, src, proxy)
             # Stdout is normally empty but for some packages can be
             # very long and is not often useful
@@ -154,6 +157,8 @@ def main():
 
     elif state == 'absent':
         if package_installed(module, name):
+            if module.check_mode:
+                module.exit_json(changed=True)
             (rc, out, err) = package_uninstall(module, name, src)
             out = out[:75]