Simple sessions

[michaeldfallen]

This PR adds simple session management using express session, with some extra functionality implemented by shimming the functions on the req.session and req.sessionStore.

Goals for sessions:

• -Ability to explicitly create a session- - Complete, provided by req.session.generate()
• Middleware / Step to create a session - todo
• -Ability to enforce that a session- - Complete, provided by req.session.active()
• Middleware to enforce a session - todo
• Middleware / Exit step to destroy a session - todo
• Per record encryption - to do

[codecov-io]

Codecov Report

Merging #13 into master will increase coverage by 0.82%.
The diff coverage is 98.88%.

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
+ Coverage   98.41%   99.23%   +0.82%     
==========================================
  Files           6        7       +1     
  Lines          63      131      +68     
==========================================
+ Hits           62      130      +68     
  Misses          1        1

Impacted Files	Coverage Δ
src/services/sessions/shims.js	100% <100%> (ø)
src/Journey.js	100% <100%> (ø)	⬆️
src/services/sessions.js	97.56% <97.36%> (+3.44%)	⬆️

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[michaeldfallen]

@KarolJastrzebski can you make codecov use the .eslintrc.json config from the repo? 27 comments that conflict with my local linting.

[dtaylor7]

perhaps pull domain from config also?