[FEATURE] Send,Exchange: Show Network Fee in confirmation page

Send
![2014-12-25-202439_1366x768_scrot](https://cloud.githubusercontent.com/assets/395821/5553984/15279038-8c74-11e4-9f55-948778199058.png)

Exchange
![2014-12-25-202348_1366x768_scrot](https://cloud.githubusercontent.com/assets/395821/5553988/23908062-8c74-11e4-8155-6296c56a3985.png)

https://wiki.ripple.com/Transaction_Fee#Base_Fees says base fee is set at 10 fee units.

Proof why 0.0120 XRP makes sense:
https://www.ripplecharts.com/#/graph/BB0D83DAC757FFA51255442E0E241EF86AF226F54EC58D008B6C2F23486ED913
"XRP change: 94.636204 XRP → 94.624204 XRP (–0.012 XRP)"

Would be better if this "10" value is obtained from ripple-lib rather than hardcoded.