Add Promise shim to entry

[agubler]

Type: bug

The following has been addressed in the PR:

• There is a related issue
• All code has been formatted with prettier
• Unit or Functional tests are included in the PR

Description:

Include the @dojo/framework/shim/Promise module in the main entry point, this is to ensure that the bootstrap plugin works for IE11.

Related to dojo/webpack-contrib#140

[codecov]

Codecov Report

Merging #263 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #263   +/-   ##
=======================================
  Coverage   51.88%   51.88%           
=======================================
  Files          10       10           
  Lines         638      638           
  Branches      162      162           
=======================================
  Hits          331      331           
  Misses        307      307

Impacted Files	Coverage Δ
src/base.config.ts	23.15% <ø> (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 1995cac...cf700a7. Read the comment docs.