Implement GET /api/v1/checks/ for listing existing checks

Don't show ping URLs -- gmail converts them to clickable links, and people click on them.

Using backend name django.db.backends.postgresql

Using new backend name which come with Django 1.9 django.db.backends.postgresql instead of django.db.backends.postgresql_psycopg2

Change github URL from SSH to HTTPS in installation instructions.

Add VictorOps integration

Use X-Forwarded-For and X-Forwarded-Proto headers, instead of X-Real-IP and X-Scheme

Add healthcheck UA to inform server about identity

test fix

Adding "healthcheck.io" as User-Agent to inform webhook handler server about request is specific from healthcheck.

remove channel should always redirect even if removal fails

defer inserting the password field into the dom

dont include tests in coverage calculation