Linting docs, test and build changes

[rgulewich]

This includes:

• Adding linting instructions to the README
• Fixing a build issue when you've been doing multiple builds on the same machine
• Allowing the docker in docker test timeout to be overridden
• A minor Makefile comment fix

[sargun]

-1t

[sargun]

Wait, what's wrong with selecting on latest?

[rgulewich]

-1 is the default when ls is not run in a shell. Latest is the symlink: we want to grab the source file here.

[codecov]

Codecov Report

Merging #187 into master will increase coverage by 9.81%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #187      +/-   ##
==========================================
+ Coverage   21.62%   31.44%   +9.81%     
==========================================
  Files          66       66              
  Lines        8393     8393              
==========================================
+ Hits         1815     2639     +824     
+ Misses       6365     5435     -930     
- Partials      213      319     +106

Impacted Files	Coverage Δ
filesystems/watcher.go	62% <0%> (+3.71%)	⬆️
config/config.go	97.1% <0%> (+4.34%)	⬆️
uploader/copy.go	50% <0%> (+5%)	⬆️
api/netflix/titus/agent.pb.go	22.35% <0%> (+5.63%)	⬆️
executor/runtime/docker/capabilities.go	88.88% <0%> (+11.11%)	⬆️
executor/runner/runner.go	60.62% <0%> (+11.87%)	⬆️
executor/runtime/container.go	91.3% <0%> (+13.04%)	⬆️
filesystems/xattr/degrading_utils.go	75% <0%> (+13.63%)	⬆️
filesystems/xattr/degrading_linux.go	89.28% <0%> (+14.28%)	⬆️
executor/drivers/titusdriver.go	84% <0%> (+16%)	⬆️
... and 7 more