Make all options given to kuzzle constructor writable

[benoitvidis]

Description

In some circumstances, we may want to use the same kuzzle object and change its options, for instance to switch to another environment.

This PR allows to update any possible option given to Kuzzle constructor.

Notably, this allows to switch the connection mode back from or to ssl on the current kuzzle instance, without having to create a new object.

Linked issue

kuzzleio/kuzzle-admin-console#154

Linked PRs

kuzzleio/documentation#113

[codecov-io]

Codecov Report

Merging #188 into 4.x will decrease coverage by -0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              4.x     #188      +/-   ##
==========================================
- Coverage   99.45%   99.39%   -0.07%     
==========================================
  Files          16       16              
  Lines        1665     1665              
  Branches      441      441              
==========================================
- Hits         1656     1655       -1     
- Misses          9       10       +1

Impacted Files	Coverage Δ
src/Kuzzle.js	99.45% <ø> (-0.19%)	❌

---

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 b5de17a...d749587. Read the comment docs.

[scottinet]

This needs to be documented, with a visible warning explaining to users that changing these parameters won't take effect until an entirely new connection is created.