#444 implement multiple environments functionality

[filippomc]

Closes #444

Implemented solution: can specify harness-deployment -e env1-env2

How to test this PR: Run harness-deployment -e dev-prod. A pipeline file deployment/codefresh-dev-prod.yaml is created.
Values in there and in deployment/values.yaml will contain the values from the variuous *-dev and *-prod configuration files

Sanity checks:

• The pull request is explicitly linked to the relevant issue(s)
• The issue is well described: clearly states the problem and the general proposed solution(s)
• From the issue and the current PR it is explicitly stated how to test the current change
• The labels in the issue set the scope and the type of issue (bug, feature, etc.)
• All the automated test checks are passing
• All the linked issues are included in one milestone
• All the linked issues are in the Review/QA column of the board
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Breaking changes (select one):

• The present changes do not change the preexisting api in any way
• This PR and the issue are tagged as a breaking-change

Possible deployment updates issues (select one):

• There is no reason why deployments based on CloudHarness may break after the current update
• This PR and the issue are tagged as alert:deployment

Test coverage (select one):

• Tests for the relevant cases are included in this pr
• The changes included in this pr are out of the current test coverage scope

Documentation (select one):

• The documentation has been updated to match the current changes
• The changes included in this PR are out of the current documentation scope

Nice to have (if relevant):

• Screenshots of the changes
• Explanatory video/animated gif