Re-vamp of Development Guide
infra_providers: Refresh

* Added possibility to refresh the query to speed things up
* Made the check for settings use the refresh if the data have not come yet
Cleanup and slight additions to docs
vms_subpages/details.py: wait_for
pages/cloud/instances/__init__.py wait_for
Merge pull request #300 from mfalesni/provider_refresh

Provider refresh + wait_fors
Merge pull request #299 from psav/docs_update

Docs update