Add support for Ebakus network

[ziogaschr]

This PR adds support for the ebakus network (https://www.ebakus.com/) and other ebakus fork networks, which are backwards compatible with Ethereum. Ebakus has high throughput and low latency (DPOS 1sec blocks). It’s main innovation however is the way it handles transaction fees. Instead of paying with gas for a transaction, you have to perform some Proof of Work (PoW) client side. Target difficulty for PoW dynamically adjusts based on network congestion to better mitigate spam. Moreover ebakus also introduces ebakusDB, a schema defined in-contract database that supports tables and indexes to enable smart contract developers handle large datasets with ease without having to adopt hybrid solutions. Having high throughput, low latency and more importantly no fees in order to send transactions ebakus opens decentralized Apps to the general public and enables developers to design better user experiences.

So this PR does three things:

• adds calculation of PoW for Ebakus only networks
• adds the Ebakus mainnet and testnet in the list of available networks
• removes the gas price input boxes from the UI

Once you accept this PR or you inform us on your intent to merge it and add ebakus support, we will create the following new PRs:

• replace the "Send Ether" localised text, with three new string "Send", "Ether", "Ebakus"
• fix transaction's "speed up" and "retry" logic
• allow the user to set custom work amount (this is for later)

[ziogaschr]

It seems that the e2e tests can't pass.
We haven't touched that flow, but by examining the test flow it seems that it tries to click a button matched by a CSS class. While in the actual UI there are two buttons with this class.

So I am not sure if it will be able to open the correct dialog. Furthermore, I wasn't able to run the e2e tests locally.

Any suggestions on how to tackle this one? Is someone else working on this, in a separate PR? Shall we handle it here?

[whymarrh]

Hey, @ziogaschr, thanks for taking the time to work on this and for being so eager to get the build passing. The set of networks we offer via the network list can't be extended to include everyone's networks and we don't have a way of honestly choosing among the various networks (see also Pocket's #6783, xDai's #7492, and Incubed's #8117).

I'm going to close this for now. We can open up an issue to track and discuss how we might best make this network available to our users. #3604 and #5101 are relevant—feel free to comment there as well—ideally we should have a way to allow sites (maybe plugins even?) to add new networks. We welcome new ideas here. We also wrote up an article mid-2018 describing this our views on this in more detail.