Fix gitlab_* module boolean parameter declaration (#2385)

Without these fixes using the modules would result in the following error:
  implementation error: unknown type <type 'bool'> requested for validate_certs

lib/ansible/modules/extras/source_control/gitlab_group.py

@@ -146,7 +146,7 @@ def main():
     module = AnsibleModule(
         argument_spec=dict(
             server_url=dict(required=True),
-            validate_certs=dict(required=False, default=True, type=bool, aliases=['verify_ssl']),
+            validate_certs=dict(required=False, default=True, type='bool', aliases=['verify_ssl']),
             login_user=dict(required=False, no_log=True),
             login_password=dict(required=False, no_log=True),
             login_token=dict(required=False, no_log=True),

lib/ansible/modules/extras/source_control/gitlab_project.py

@@ -297,7 +297,7 @@ def main():
     module = AnsibleModule(
         argument_spec=dict(
             server_url=dict(required=True),
-            validate_certs=dict(required=False, default=True, type=bool, aliases=['verify_ssl']),
+            validate_certs=dict(required=False, default=True, type='bool', aliases=['verify_ssl']),
             login_user=dict(required=False, no_log=True),
             login_password=dict(required=False, no_log=True),
             login_token=dict(required=False, no_log=True),
@@ -305,11 +305,11 @@ def main():
             name=dict(required=True),
             path=dict(required=False),
             description=dict(required=False),
-            issues_enabled=dict(default=True, type=bool),
-            merge_requests_enabled=dict(default=True, type=bool),
-            wiki_enabled=dict(default=True, type=bool),
-            snippets_enabled=dict(default=True, type=bool),
-            public=dict(default=False, type=bool),
+            issues_enabled=dict(default=True, type='bool'),
+            merge_requests_enabled=dict(default=True, type='bool'),
+            wiki_enabled=dict(default=True, type='bool'),
+            snippets_enabled=dict(default=True, type='bool'),
+            public=dict(default=False, type='bool'),
             visibility_level=dict(default="0", choices=["0", "10", "20"]),
             import_url=dict(required=False),
             state=dict(default="present", choices=["present", 'absent']),

lib/ansible/modules/extras/source_control/gitlab_user.py

@@ -263,7 +263,7 @@ def main():
     module = AnsibleModule(
         argument_spec=dict(
             server_url=dict(required=True),
-            validate_certs=dict(required=False, default=True, type=bool, aliases=['verify_ssl']),
+            validate_certs=dict(required=False, default=True, type='bool', aliases=['verify_ssl']),
             login_user=dict(required=False, no_log=True),
             login_password=dict(required=False, no_log=True),
             login_token=dict(required=False, no_log=True),