feat: support sandbox instances of salesforce

[zacharygolba]

Closes #3

---

Adds sandbox support by adding the ability to pass a --sandbox (or -s, for short) flag to the glide init command. When --sandbox is passed to the init command, a boolean "sandbox": true property is added to the resulting json file. This option instructs the authentication layer of glide to use the correct login url (https://test.salesforce.com).

Users of glide will be able to generate an additional json config for their sandbox instance by running the init command with the additional [path] argument to specify the file name that best suits their projects naming conventions.

glide init https://my-sandbox-instance.salesforce.com glide.sandbox.json --sandbox

To serve data from their sandbox instance rather than using the default production glide.json file, they can simply provide the filename as a positional argument to the serve command.

glide serve glide.sandbox.json

[zacharygolba]

This was split up into multiple files to make it easier to maintain in the future. Each file in the events directory now represents a single lambda event handler.

[adampash]

🎉

[adampash]

Actually just realized: Can you update the Getting started docs?

[codecov-io]

Codecov Report

Merging #6 into master will decrease coverage by 0.64%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master       #6      +/-   ##
==========================================
- Coverage      50%   49.35%   -0.65%     
==========================================
  Files          11       11              
  Lines         304      308       +4     
  Branches       44       46       +2     
==========================================
  Hits          152      152              
- Misses        152      156       +4

Impacted Files	Coverage Δ
src/lib.ts	0% <ø> (ø)	⬆️
src/oauth.ts	0% <0%> (ø)	⬆️
src/main.ts	0% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3cb730d...f70af51. Read the comment docs.

[jsalva]

is this going to get merged?