Add integration test for adding series to user's collection

[php-coder]

(This is the same as #46 but because it was reverted in #1019 we need to implement it again but on RobotFramework.)

When user opens a series info page and clicks on a button for adding series to collection, he should be redirected to collection page where this series is listed.

Technical Debt for: 227b9a5 (#2)