MetaMask: Use web3.currentProvider instead of window.web3

[vitvly]

Summary

When browsing Open Bounty website with MetaMask on, it complains in Console that

MetaMask: web3 will be deprecated in the near future in favor of the ethereumProvider 
https://github.com/MetaMask/faq/blob/master/detecting_metamask.md#web3-deprecation

Solution

Following the above given document, use web3.currentProvider instead of window.web3 when calling MetaMask in application code.

[status-open-bounty]

Current balance: 0.0 ETH
Tokens: SNT: 240.00
Contract address: 0x78fb1c9c203d1f3d0ea421a7bdaf61ae6d9b5a52

Network: Mainnet
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[martinklepsch]

This should be super easy to fix by upgrading cljs-web3 to 0.19.0-0-11 and replacing the web3 constructor we defined here:

open-bounty/src/cljs/commiteth/common.cljs

Lines 10 to 11 in b76ad70

	(defn web3 []
	(gobj/get js/window "web3"))

with the one that has been added to cljs-web3 in this PR: district0x/cljs-web3#8

[debragail]

do we need to fix this anywhere else?

[debragail]

I think this was fixed?

[pablanopete]

To be revoked @andytudhope