Let ancestors access modal to prevent exception

Let the current call stack clear so ancestor components accessing this
modal can still access it before it is unmounted. Without deferring,
React throws an exception in `ReactMount.findComponentRoot` when the “X”
or “Cancel” button is clicked.
bug fix: New app doesn't immediately display app list
added 'unknown' until running tasks get updated
review: Moving task running to model
review: Discarding wrong changes
Merge pull request #301 from mesosphere/prevent-modal-exception

Let ancestors access modal to prevent exception
Merge pull request #300 from mesosphere/bug/new-app-not-displaying-immediately

Please review
doing strict check
Adding reversible sorting to the app list
Added cursor: pointer to clickable stuff in table
helvetica, 200 as fallback font on headlines
Review: reverting style changes
Review: changing '=== undefined' to '== null'
Review: using camelCased variables
Generalising sorting into SortableCollection
Review: changing api to be setComparator
Changing default sorting of task and app list
Fixes #307 Container opts with default executor.
Merge pull request #308 from mesosphere/container-logic

Fixes #307 Container opts with default executor.
Organize feature section in README