Tasks are not overridable

[davemo]

node_modules/lineman/config/application.js defines the root tasks that lineman executes in each of its configurations common, watch, dist.

Other properties of this file are overridable in {project}/config/application.js but not the actual list of tasks due to the way tasks are fetched inside lineman/cli.js ...

    appTasks = require(__dirname + '/config/application.js').appTasks,

We need to modify this so the list of tasks is overridable or exclude them from node_modules/lineman/config/application.js so as not to confuse people. Files in the config folder in the generated project should only point to lineman/config files that contain overridable keys.

As a general note, we should probably be clearer about what we intend to be overridable. (All? None? Some with clearer docs?).