Remove "Third party" bubble disclaimer for Electrum 

As suggested by @mikehearn, it seems more reasonable to remove the "Third party" disclaimer now. Electrum is now connecting to a random server from a list of 22 servers at each startup.

~~Additionally, I'd like to suggest we replace MultiBit by Electrum as the "default" recommended wallet for Desktops for the following reasons:~~

~~Deterministic wallets ( No address reuse ).~~
~~Offers a good backup plan to the user at first start.~~
~~Easier to install ( No Java, MultiBit Linux installer has a few glitches )~~

~~Many nice features from MultiBit are also supported by Electrum, like localization and loading/saving wallets from/to files. Maybe MultiBit could be set as the default wallet again once MultiBit HD is released. Meanwhile, promoting a different wallet would promote a little more diversity.~~