Merge pull request #573 from es128/master

Skip compiling deps on initial compilation
Decrease interval time for file list to 65.
Remove modules.addSourceUrls, add config.sourceMaps.
Bump version to 1.7.0-pre.
Update changelog.
Log source map only if it exists.
Remove on / off / yes / no-s. I feel that true-false still look better.
Exposes loaded modules as globals.require.modules
Renames exposed require modules to require.cache
Merge pull request #577 from benjamincox/topics/exposemodules

Exposes loaded modules as globals.require.modules for testing convenience
Add `require.list` instead of `require.cache`.
Update bwc.
Clarify error message when building in invalid dir.
Fix file removal. Closes gh-579.
Fix source maps.
Add config.fileListInterval. Closes gh-549.
Don’t add sourceMappingURL if source maps are disabled.
Fix naive error formatting.
Add Bower support. fuck yes
Remove async.js dependency. Depend on my simple lib.