Add WelcomeActivityTest

[domdomegg]

Description (required)

Adds Android Test: WelcomeActivityTest

TODO - moved to #2644

Probably want to flesh this out a bit with some more tests. Ideally we'd have one which would swipe the correct number of times and then click 'yes', and check we were out of WelcomeActivity

Also maybe check that on beta clicking the skip tutorial exits WelcomeActivity

Also maybe check we can swipe both ways (i.e. backwards and forwards)

Also maybe check swiping beyond the proper bounds shouldn't do anything e.g. swiping left on the first page or right on the last page.

[codecov-io]

Codecov Report

Merging #2636 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #2636   +/-   ##
======================================
  Coverage    2.77%   2.77%           
======================================
  Files         259     259           
  Lines       12364   12364           
  Branches     1116    1116           
======================================
  Hits          343     343           
  Misses      11994   11994           
  Partials       27      27

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[domdomegg]

Have removed WIP tag as I think we may as well merge this, and then future PRs can flesh out the tests more. Have moved the TODOs to #2644.

[maskaravivek]

@domdomegg Is travis running these tests at all? Codacy report doesn't show any change in the coverage.

[domdomegg]

No, Travis stopped running instrumentation tests in #2595, particularly 0d203a4

[maskaravivek]

Now, that we have more instrumentation tests, it should be fine to add it back again.

[maskaravivek]

Merging this and travis instrumentation tests can be enabled in a different PR.