`lc` should abort if `lc.yml` is not present, or if `project_name` is not properly defined

[joeygibson]

Currently, if there is no lc.yml present, lc will continue working. It should stop dead in its tracks.

Also, project_name needs to be defined, either through lc.yml, or from the command line. Not having it screws up docker network creation between local and Jenkins.

[therishidesai]

In the LoadConfigFile Function, if the lc.yml file is not found it returns nil. I don't know if halting the program there is the best way to solve this since wouldn't that prevent the creation of an lc.yml file. I might be miss understanding something. https://github.com/cisco/elsy/blob/000e7dba05d45259278e89806cd5608289dfa687/main/config-file.go#L28