add last failed tx processing

[dzhambulat]

this fix checks last failed tx when user enters token address

[rstormsf]

so the issue was about to resend any failed tx by querying a tx hash

1. Implement a new route to display input box to enter txhash
2. verify if txhash is valid and it was sent to multisender contract address
3. if it is, ask etherscan.io api for the reason of tx failure if it's out of gas, then
4. parse tx input and move user to /3 screen where he can see all tx data like you do from screen 1 to 3
5. send a transaction with higher gasLimit then the previous one.

[dzhambulat]

added page /#/checktx enter tx hash, and if it failed, user may push btton "Resend transaction", and it redirects to /#/3 and he can process it and change gas in metamask.

[dzhambulat]

I have done fixes for cleaning ( I forget to commit deleting of debug alerts and other fixes before last PR). I reviewed other classes, and I think that tokenStore and gasPriceStore should be refactored, because many methods violates The Single Responsibility Principle and it was hard to me make additional features and fixes.