#34 fail stack creation if python not configured

[switch180]

Issue #, if available: #34

Description of changes:

• Remove default signal success command to CloudFormation
• Add checks to see if python3.6 is installed, and if python scripts are in the correct directory
• Failure returned if checks fail along with specific failure message, else a success is returned to CFN

Testing was done by launching a CFN stack and subtly modifying the UserData script to cause it to fail. I proved the correct status was returned each time.

In the event of failure, here's a sample message from the stack events:

WaitCondition received failed message: 'Python scripts not in workshop directory.' for uniqueId: i-0a8bf5d3102e9567d

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