Add api view for user_save
Add api for error_info
Add api for Device Info
Create serializer for User Save
Create serializer for Error Info
Create serializer for Device Info
Refactor code and modify post method for user save
Merge branch 'user-save' of https://github.com/kriwil/labster into user-save

Conflicts:
	labster/api/views.py
Fix conflict in api/views.py
Rename field in DeviceInfo from type to machine_type
Merge branch 'lab-xblock' into user-save

Conflicts:
	labster/admin.py
	labster/api_v2_urls.py
	labster/forms.py
Add test view for ErrorInfo
Add test view for DeviceInfo
Create test view for user save