build(aio): refactor dgeni packages

This is to tidy up the `author-packagse`, which currently duplicates a
lot of the configuration in the main packages. We need to
DRY this up so that we don't fall foul of a change in one being missed in
the other.

aio/tools/transforms/angular-base-package/rendering/trimBlankLines.spec.js

@@ -0,0 +1,15 @@
+var factory = require('./trimBlankLines');
+
+describe('trimBlankLines filter', function() {
+  var filter;
+
+  beforeEach(function() { filter = factory(); });
+
+  it('should be called "trimBlankLines"',
+     function() { expect(filter.name).toEqual('trimBlankLines'); });
+
+  it('should remove empty lines from the start and end of the string', function() {
+    expect(filter.process('\n  \n\nsome text\n  \nmore text\n  \n'))
+        .toEqual('some text\n  \nmore text');
+  });
+});