Rest framework (#24)

* Add rest framework for API: First Commit

* modify some shell scripts to make variable references safer; modify some python scripts to reduce the code complexity and cyclomatic complexity of functions.

* Add REST API for some webvirtcloud functions. Instance list/delete/create, compute list/delete/create, storages-network list/retrieve. Add swagger and redoc for API interface

* update requirements

Co-authored-by: herengui <herengui@uniontech.com>

instances/templates/create_instance_w2.html

@@ -19,7 +19,7 @@
     {% for field in form %}
         {% for error in field.errors %}
             <div class="alert alert-danger">
-                <strong>{{ error|escape }}</strong>
+                <strong>{{ field.label }}:</strong> <span>{{ error|escape }}</span>
             </div>
         {% endfor %}
     {% endfor %}