Adds basic support for InstanceGroupManager

[modeswitch]

• Basic instance support (exists, get, getMetadata, etc).

• Supports resize as well.

• Partially addresses Bindings for Instance Group Managers? #103.

• Tests and linter pass

• Code coverage does not decrease (if any source code was changed)

• Appropriate docs were updated (if necessary)

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[modeswitch]

This is ready to be reviewed now. I don't know how to check the status on the automated checks.

[codecov]

Codecov Report

Merging #263 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #263      +/-   ##
==========================================
+ Coverage   99.11%   99.13%   +0.02%     
==========================================
  Files          19       20       +1     
  Lines        1473     1509      +36     
==========================================
+ Hits         1460     1496      +36     
  Misses         13       13

Impacted Files	Coverage Δ
src/zone.js	100% <100%> (ø)	⬆️
src/instance-group-manager.js	100% <100%> (ø)

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[JustinBeckwith]

This is awesome!

[modeswitch]

@JustinBeckwith I think the code coverage should be back up on zone.js. I'm not sure why the docs links are broken though.

[modeswitch]

Can I run the ci/kokoro tests locally?

[modeswitch]

@JustinBeckwith Docs added for InstanceGroupManager. I think that should fix the last of the CI complaints. Can you re-run kokoro?

[JustinBeckwith]

Thanks for being patient with this one :)

[modeswitch]

Heh, 3 hours on a Sunday is tolerable :P

[toots]

Awesome, thanks for the work!