DCOS: added retry logic to download and install packages

[dmitsh]

added retry logic to download and install packages during DCOS node provisioning

[codecov]

Codecov Report

Merging #3009 into master will decrease coverage by 0.04%.
The diff coverage is 93.75%.

@@            Coverage Diff            @@
##           master   #3009      +/-   ##
=========================================
- Coverage   50.75%   50.7%   -0.05%     
=========================================
  Files          97      97              
  Lines       14699   14678      -21     
=========================================
- Hits         7460    7443      -17     
+ Misses       6539    6536       -3     
+ Partials      700     699       -1

Impacted Files	Coverage Δ
pkg/acsengine/engine.go	62.38% <93.75%> (-0.21%)	⬇️
pkg/acsengine/transform/transform.go	63.17% <0%> (+0.12%)	⬆️

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[jackfrancis]

/approve
/lgtm

[acs-bot]

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