closes #53 - add influxDB

[Ulisseus]

InfluxDB was chosen over TimescaleDB mostly because latter requires older versions of Postgres and maintaining multiply psqls on the same machine is rather annoying. It's also more popular at least for now.

Since this PR adds new influxDB button welcome page snapshots were updated.

To safely merge:

• InfluxDB 1.8 needs to be installed
• INF_HOST and INF_PORT environment variables should be configured, by default it's localhost and 8086
• src/routes/renderRoutes.js line 22 Influx: "PRODUCTION INFLUXDB HOST", needs to be changed to whatever host will be used in production

Proofreading of influxDB tutorial is appreciated.

[codecov[bot]]

Codecov Report

Merging #244 into master will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #244   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           13        14    +1     
  Lines          494       540   +46     
  Branches        55        63    +8     
=========================================
+ Hits           494       540   +46     

Impacted Files	Coverage Δ
database/influx/influx.js	100.00% <100.00%> (ø)
lib/util.js	100.00% <100.00%> (ø)
src/routes/renderRoutes.js	100.00% <100.00%> (ø)
src/routes/userRoutes.js	100.00% <100.00%> (ø)
src/server.js	100.00% <100.00%> (ø)

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