Refactor local build process.
Hide Drupal-specific code or move it to the Drupal toolstack.
Blacklist certain files from being symlinked while building Drupal.
Move ensureDrushInstalled to the Drupal toolstack, meaning it can run the check again without being coupled to PlatformCommand.
Remove redundant/risky rmdir() in Drupal makefile build.
New default .gitignore files for different build modes.

Removes unused Symfony gitignore file.
Remove 'default' app name.
Consistency - platform build -h should show all options if there is no projectRoot.
Fix undefined argument errors.
EnvironmentListCommand does need the currentEnvironment property.

Plus: simplify DomainAddCommand
Fix get errors, and move shared/files creation to the Drupal toolstack.
Minor fixes.
Symlink settings*.php for makefile build.
getEnvironments() improvements
Merge pull request #147 from pjcdawkins/refactor-build

Refactor local build process
Fix: build settings not passed to toolstack.