Add own web3-eth version

[patitonar]

This PR add web3 library inside the repo on lib directory. This web3 version is based on 1.0.0-beta.37 and includes getChainId method on web3-eth module.

preinstall script was added to correctly build and include the web3 library as dependency for the app.

Closes https://github.com/poanetwork/bridge-ui/issues/204, using this version, we avoid the issues introduced before. While testing, only when I sent from ETC to ETH the false error of tx revert even if it was successful was present. So now we log the error but avoid stopping the UI flow

[netlify[bot]]

Deploy preview for kind-kilby-95344f processing.

Building with commit fe27eba69b51afe173103dd07c70ebdabcd047ee

https://app.netlify.com/sites/kind-kilby-95344f/deploys/5c9d2c416f5bc400088a6713

[patitonar]

I refactored the solution. We go back to the initial 1.0.0-beta.30 version of web3 that used to work correctly. I added the modified version of web3-eth that includes getChainId on lib folder. After installing dependencies, this file overrides the one installed on node_modules.

I made more tests and with this changes and now the issue of false error of tx even if it was successful is now gone! So it seems that 1.0.0-beta.37 was causing that one too.

[coveralls]

Pull Request Test Coverage Report for Build 432

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 10.324%

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Totals
Change from base Build 425:	0.03%
Covered Lines:	48
Relevant Lines:	443

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💛 - Coveralls