Cleaning zip packages correctly during uninstall/update.

[vrdmr]

Description

Cleaning up zip packages correctly during uninstall and update.

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PR information

• The title of the PR is clear and informative.
• There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
• Except for special cases involving multiple contributors, the PR is started from a fork of the main repository, not a branch.
• If applicable, the PR references the bug/issue that it fixes in the description.
• New Unit tests were added for the changes made and Travis.CI is passing.

Quality of Code and Contribution Guidelines

• I have read the contribution guidelines.

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This change is 

[narrieta]

@vrdmr Travis failed

[vrdmr]

@narrieta - Yes. Working on fixing the tests.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (develop@9687794). Click here to learn what that means.
The diff coverage is 70%.

@@            Coverage Diff             @@
##             develop    #1642   +/-   ##
==========================================
  Coverage           ?   66.78%           
==========================================
  Files              ?       78           
  Lines              ?    11237           
  Branches           ?     1577           
==========================================
  Hits               ?     7505           
  Misses             ?     3406           
  Partials           ?      326

Impacted Files	Coverage Δ
azurelinuxagent/ga/exthandlers.py	83.38% <70%> (ø)

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[pgombar]

LGTM!

[larohra]

LGTM