Adding sponsor logo and additional text to landing page (FE)

[MariusJulius]

Logo file here: https://pilv.rtk.ee/s/kJ4AWiKkLDdeqKb (use colored) Instructions: https://pilv.rtk.ee/s/K9S6AqY2jKEmsTg (lk 20 - no need to check) Figma

To-do:

• Add logo (of the Euroopa Regionaalarengu Fond) to the landing page (before the user logs in) and also to home page after login
• Adding additional text and link to landing page (as in figma) : "Eesti Keele Instituudi masintõlkekeskkonna kasutamiseks vajuta siia", URL https://mtee.eki.ee/

[PlaksoBirgit]

@martinepai please add the logo to the design. Please tag us when it's done.

[plakitkelly]

Tested in 15.12 - It's OK