Profile remove command

[segfaultxavi]

New profiles can be generated or imported but they cannot be removed unless ~/symbol-cli.config.json is manually edited.

When experimenting with symbol-bootstrap, for example, I create lots of short-lived profiles which accumulate and pollute my profiles list. I would like to be able to remove them from the command line.

Issue #206 suggests the addition of an Update command. With this issue we would have the whole CRUD command set :)