Changes to make it easier for new developers to come onboard and changes to environment.prod.ts to make it safer for the current deployment script to replace specific configuration values.

[apspestana]

Changes to make it easier for new developers to come onboard:

• In package.json changed version of app from "0.1-SNAPSHOT" to "0.0.1", because I was having the error "npm ERR! Invalid version: "0.1-SNAPSHOT"" when running "npm link" (which I needed to run because of error "You seem to not be depending on "@angular/core" and/or "rxjs". This is an error." when runnning "ng serve").
• Added info to the "get started" section of README.md to make it easier for new developers to get up and running.
• Added info to the "developer guide" section of README.md.
• Did changes so that all files pass linting (command "ng lint").
• Updated version of dependencies @babel/core, @babel/preset-env, @babel/register and @babel/compat-data so that the command "ng build --prod" executes successfully. Before updating the version of the specified dependencies, the build command ended with error "An unhandled exception occurred: Cannot find module '/Users/apestana/src/cerberus-angular/node_modules/@babel/compat-data/data/corejs3-shipped-proposals' See "/private/var/folders/dl/_bm9khtn3t956m6_z1nrl3t40000gn/T/ng-s7qnVD/angular-errors.log" for further details.".

Also, changed environment.prod.ts to make it safer for the deployment script (as implemented by BD) to replace specific configuration values (instead of a value we now have a placeholder, for the deployment script to search for the placeholder and replace it with a value).