Add unit test for story.parseMultiple

- make sample story data global to make it visible in all tests
- test if story.parseMultiple can parse sample story correclty

There's no such method yet, but there's story.getAllFromHtml.
Rename story.getAllFromHtml to story.parseMultiple
Add unit test for story.parseMultiple: incorrect argument handling
Add story.containsStory

This private method returns true if first argument contains enough data
for story parsing.
It will be used by parse and parseMultiple methods to determine if
supplied html actually contains at least one story.
Use story.containsStory in story.parse

See c10199.
Use story.containsStory in story.parseMultiple

See c10199.
Merge branch 'develop'
Move header code to header.js

- add header.js to manifest
- remove header related code from app.js
- fire app.beforeShow event before animating application html
- in header.js listen to this event and then append header to .page

Also fire app.afterShow and app.afterStart events after animation.
Add header.js to test/index.html

Just for consistency.
Add unit test for story.getAllOnPage
Add unit test for story.render: single story render check
Add unit test for story.render: multiple story render check
Add unit test for app.start: must throw error if already started
Add unit test for app.stop: must throw error if already stopped
Add unit test for app.getEnabled
Fix unit test for app.getEnabled
Rename app.checkEnabled to app.getEnabled

Similarity in method names is good.
Add check if already running (or not) in app.start and app.stop
Add app.getIsRunning
Fix "app" test module setup: check app state before starting/stopping it