Adding HTTPS serve

[rorticus]

I once liked the HTTP service,
but lately it's making me nervous,
a few lines of code,
an HTTPS mode,
now safe and secure it preserves us.

If .cert/server.key and .cert/server.crt are detected, dojo build will now serve files via HTTPS.

Resolves #43

[codecov]

Codecov Report

Merging #153 into master will increase coverage by 1.17%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #153      +/-   ##
==========================================
+ Coverage      56%   57.17%   +1.17%     
==========================================
  Files           8        8              
  Lines         475      488      +13     
  Branches      113      116       +3     
==========================================
+ Hits          266      279      +13     
  Misses        209      209

Impacted Files	Coverage Δ
src/main.ts	93.75% <100%> (+0.62%)	⬆️

---

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 7e6b785...92dc460. Read the comment docs.

[mwistrand]

Nice!