Update dependencies

[brandondoran]

• Bumps babel to 7.2.3 to 7.8.4
• Drops dependency of babel runtime
• Set target babel compilation to Node 8 (current oldest supported version)
• Bumps eslint from 4.19.0 to 6.8.0
• Bumps eslint-config-airbnb-base from 12.1.0 to 14.0.0
• Bumps jest from 24.1.0 to 25.1.0
• Bumps codecov, cross-env, nockm and rimraf to latest
• Bumps async to latest

[brandondoran]

Codecov Report

Merging #79 into master will not change coverage by %.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #79   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines           74        74           
  Branches        19        19           
=========================================
  Hits            74        74           

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[codecov-io]

Codecov Report

Merging #79 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master    #79   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           3      3           
  Lines          74     74           
  Branches       19     19           
=====================================
  Hits           74     74

---

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 2e37d72...273d884. Read the comment docs.