Adding the required option

[hecflores]

Adding the required property. This property will be used to define if environment variables are required and also to choose which ones are required.

• required
  • array - array of environment variables that are required. Will fail if they dont exists.
  • boolean - true (all are required), false (none are required)

[hecflores]

@boopathi let me know if there is anything needed from me for this.

[hecflores]

@boopathi is there a reason my build is failing... Is there some other PR that is working on the dependency issue?