Fix selenium test

[ricardobranco777]

This PR fixes Selenium test for PCW:

• Updates Selenium version.
• Builds base image before building pcw itself.
• Adds a sleep before creating user in database to allow for the migrations at startup to run.
• Tidies up the Xpaths for the login & logout buttons.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.17%. Comparing base (8d96826) to head (8ec0cb6).
Report is 11 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #371   +/-   ##
=======================================
  Coverage   78.17%   78.17%           
=======================================
  Files          22       22           
  Lines        1676     1676           
=======================================
  Hits         1310     1310           
  Misses        366      366           

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[asmorodskyi]

LGTM