Added lifetime for the Resources in Label definition

[sparshev]

With lifetime timeout we can be sure the application resource will not be executed forever if something bad happened and based on this timeout fish node will be able to do some heuristics on how much time left till provisioning the next resource (#38).

The duration is set in standard golang format as string "1h2m3s", if it's empty or 0 - the default from fish config will be used. And if it's negative (like "-1s") then the resource should exist until user say so by deallocating it.

This change really helps with clouds where we certainly don't need to left the resources for long time.

Related Issue

fixes: #28

How Has This Been Tested?

Automatically

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.