Optimize SVGs

`chrome.svg`:
  * __before__: 7275
  * __after__: 3447 
  * __reduction__:  3828 [52.62%]

`chromium.svg`:
  * __before__: 10722
  * __after__:  4362
  * __reduction__: 6360 [59.32%]

`firefox.svg`:
  * __before__: 45185
  * __after__:  34243
  * __reduction__: 10942 [24.22%]

`ie.svg`:
  * __before__: 9877
  * __after__:  5705
  * __reduction__: 4172 [42.23%]

`opera.svg`:
  * __before__: 14890
  * __after__:  13484
  * __reduction__: 1406 [9.44%]