Concatenate templates

[sixfeetover]

Allow consult to merge multiple templates together.

Consider the scenario:

# consult.yml
templates:
  paths:
    - database.yml.erb
    - database.development.yml
  dest: config/database.yml

In this situation, database.development.yml can be in .gitignore, and allow individual developers to configure it as they see fit, for their own local docker containers. If the file doesn't exist (e.g., in production), consult simply ignores it.

[sixfeetover]

Closed by #14.