fix dependencies for --production flag with npm

[alexrqs]

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Description

this pr changes 2 devDependencies to actual dependencies to avoid the error mentioned on #179

"errorType": "Runtime.ImportModuleError",
"errorMessage": "Error: Cannot find module 'https-proxy-agent'",

References

this fixes #179

Testing

import as dependency and use npm install --production and should work fine

[drsaeva]

Please add a fix for this line:

https://github.com/auth0/node-jwks-rsa/blob/master/src/wrappers/request.js#L4

The http-proxy-agent should have been imported there, but is not, and is therefore a dead dependency.