Style "update is available" notification

[let4be]

I had some time and implemented

https://github.com/lavab/web/issues/655 https://github.com/lavab/web/issues/654

so we could notify our users there is new version available and we could fix some bugs easier(those that requires user to logout && login again)

[JPL1]

Suggested rewording:

To update to the newest version of Lavaboom click the button below.

Note: In order to perform this upgrade we will need to log you out and you will need to log back in again using your Lavaboom login and password.

[let4be]

Sounds better :)

[vviikk]

@vLooz is giving me new designs for modal windows across the site. Will wait for those.

[vLooz]

See here: https://github.com/lavab/web/issues/873 @piggyslasher :-)