update MEW logos

[hackmod]

How about to fix the MEW logo? this is just a suggestion :)

• remove some glitches
• embolden M/W shape
• misc fixes (fixed e shape, blur the shadow of the e shape, add some highlighting)

TODO

• [x] update all icons found at app/images/fav/
  • add 64x64 ico to favicon.ico
• [ ] update images/myetherwallet-logo-banner.png
• [ ] update images/myetherwallet-logo.png