Make Promote() use cv version which user defined in YAML, not just latest

[lvw5264]

Pull request verbatim from the tested code in issue #62. To reiterate:

I had a use case where we don't use composite content views, yet I wanted the promote command to use the content view version I defined. However, for some reason the promote command always uses the latest and does not check for the version the user defined in :cv: under YAML at all.

I suggest a solution in the code below, allowing the user specified version in YAML to be used, as well as latest. since I just hacked this together by combining aspects of the update() function, I will just paste the promote() function I made.

Also when the request in promote() gave a 400 bad request, as the exception was not handled, so I added a rescue statement, which now helpfully tells the command line user that they "Cannot promote environment out of sequence. Use force to bypass restriction.".

The YAML I use, where i have Library.yaml , dev.yaml (always kept up to date with Library), test.yaml, prod.yaml.

# prod.yaml
:settings:
  :user: admin
  :pass: YOURPASSWORD
  :uri: https://localhost
  :timeout: 300
  :org: 1              # always 1 
  :lifecycle: 6        # ID of the lifecycle, not always obvious
  :checkrepos: true    # check if the latest repo packages are already in the curre
nt content view
  :promote_cvs: true   # don't use composite content views for publishing
  :keep: 5
  :wait: false         # should cvmanager wait for tasks to finish, or run them in 
the background
  :sequential: 1       # run only one task at once
:cv:
  rhel7: 10.0   # I specifically want version 10 and not the latest 12
:publish:
  - rhel7
:promote:
  - rhel7

[Rocco83]

This is already in
Rocco83@c6fb789#diff-f7030f12fde1940699c8be343ca6945aR302
Am i wrong?

[kallies]

This change introduces the issue, that regular promotes are not possible anymore:

We use

cvmanager --config=cvmanager-201904.yaml --user=cvmanager --pass=cvmanagerpass --uri=https://satellite.example.com --organization-id=1 --force --wait --description 'promote to lce 2 201904' promote --to-lifecycle-environment 2

with the following config

---
:settings:
  :timeout: 300
  :keep: 8
  :verify_ssl: true
:ccv:
  ccv-lin7:
    cv-lin7-os: 123.0
:publish:
  - cv-lin7-os
:promote:
  - ccv-lin-7

For explicit CCV version promotes we use (with this PR included in cvmanager)

---
:settings:
  :timeout: 300
  :keep: 8
  :verify_ssl: true
:cv:
  ccv-lin7: 10.0
:ccv:
  ccv-lin7:
    cv-lin7-os: 123.0
:publish:
  - cv-lin7-os
:promote:
  - ccv-lin-7