Fixes behavior of ipavault when no user, service or shared is given.

IPA CLI allows the creation of vaults without specifying user, service or a
shared vault, defaulting to create a user vault for the `admin` user. The
vault module, required that one of user, service or shared was explicitly
provided, and this patch makes the module behave like the CLI command.

Tests were added to reflect this change.

tests/vault/test_vault.yml

@@ -65,13 +65,54 @@
       shared: True
       state: absent
 
-  - name: Ensure service vaults are absent
+  - name: Ensure standard vault is absent
+    ipavault:
+      ipaadmin_password: SomeADMINpassword
+      name: stdvault
+      state: absent
+
+  - name: Ensure service vault is absent
     ipavault:
       ipaadmin_password: SomeADMINpassword
       name: svcvault
       service: "HTTP/{{ groups.ipaserver[0] }}"
       state: absent
 
+  # tests
+  - name: Ensure standard vault is present
+    ipavault:
+      ipaadmin_password: SomeADMINpassword
+      name: stdvault
+      vault_type: standard
+    register: result
+    failed_when: not result.changed
+
+  - name: Ensure standard vault is present, again
+    ipavault:
+      ipaadmin_password: SomeADMINpassword
+      name: stdvault
+      vault_type: standard
+    register: result
+    failed_when: result.changed
+
+  - name: Ensure standard vault is absent
+    ipavault:
+      ipaadmin_password: SomeADMINpassword
+      name: stdvault
+      vault_type: standard
+      state: absent
+    register: result
+    failed_when: not result.changed
+
+  - name: Ensure standard vault is absent, again
+    ipavault:
+      ipaadmin_password: SomeADMINpassword
+      name: stdvault
+      vault_type: standard
+      state: absent
+    register: result
+    failed_when: result.changed
+
   - name: Ensure symmetric vault is present
     ipavault:
       ipaadmin_password: SomeADMINpassword