Add ping endpoint, closes #155

[dougppaz]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 772

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 98.119%

---

Totals
Change from base Build 763:	0.0%
Covered Lines:	1356
Relevant Lines:	1382

---

💛 - Coveralls

[eltonplima]

We can improve this code like that:

def check_database_connection(**kwargs):
        for conn in connections.all():
            try:
                conn.cursor()
                return True
            except OperationalError:
                return False
        return False

[eltonplima]

You are checking only default database connection. If you add N databases and if one of these databases goes down, your system return that's all is ok, and it's not true.
Check my previous consideration to a possible solution.