fix(NgStyle): make NgStyle export expressions

Closes #993
chore(Travis): Increase browserNoActivityTimeout to prevent build failures
chore(docgen): Generate from lib directory instead of packages.

closes #1024
feat(NodeAttrs): Node attributes don't get initialized by NodeAttrs when
setting up observing.

In case an element does not have a value set for a propertyv, that
property is not automatically initialised. For example:

  <div test foo="bar">

will cause ElementBinder to register observer (which will in turn cause
initialisation) on property foo (of the directive) to bar, but if we try
using

  <div test>

foo property will not be initialised.