Upgrade all dependencies on web3/web3-* v1.0.0-beta.37 to v1.2.1.
Make various adjustments related to the previous convention of
`"web3": "1.0.0-beta"` in `embark.json` signifying that embark's own web3
dependency should be used in dapp builds.
Fix bugs in library manager, including a switch from using the
live-plugin-manager package to using npm in a child process to install
`"versions"` dependencies specified in `embark.json` when a specified version
doesn't match up with embark's own version for that package.
Avoid race conditions when installing `"versions"` by completing all installs
prior to starting other services. If an install fails, then after all the
installs have completed or failed the embark command will exit with error.
Change various comments and update docs to reflect the new default of web3
v1.2.1.
Michael Bradley
dependabot-preview[bot]
Pascal Precht