Warn on invalid output-path

Add unit tests
Make blueprintLookupPaths return [] outside projects

Fixes #1684
Upgrade broccoli-ember-hbs-template-compiler to 1.6.1
Merge pull request #1710 from quaertym/master

Upgrade broccoli-ember-hbs-template-compiler to 1.6.1
Merge pull request #1708 from jgwhite/blueprint-lookup-paths-outside-projects

Make blueprintLookupPaths return empty array outside projects
LiveReload filter patterns

Will allow a Project to add its own patterns for which the LiveReload
server can use to ignore certain file changes.
Merge pull request #1706 from bcardarella/bc-live-reload-filter-patterns

LiveReload filter patterns
Merge pull request #1649 from selvagsz/prevent-deleting-of-repo-for-invalid-outputpath

Prevent deletion of files when invalid output-path is provided