[Spike] Analyze possibility of move to epam UUI

[NadezhdaKatcman]

There is an idea to move miew-app from bootstrap to UUI.
Try to analyze miew-app code and UUI lib from the following view points:

• Difference in design (does UUI implement everything we use? how far their design is from us?)
• Browser and Devices limitations of UUI (we need Miew to work in different browsers and on different devices)
• Other pros and cons
• Draft estimation