Linkify hostname/port combos in task list

A common use case for task lists is finding the hostname and random port
assigned to a given task. Linkify them where possible. For multiple
ports, linkify the port numbers.

* Use same font color for hover/focus link states as `.btn-primary`.
* Move host/port formatting from model to component because it creates
  anchors specific to TaskListItemComponent.
Make `<th>` wrapping checkbox clickable

This mimics behavior of the rows below: click the checkbox or the
wrapping table cell.
Merge pull request #316 from mesosphere/linkify-task-hostname-port

Linkify hostname/port combos in task list
Compile only *.jsx files during asset compilation

* Use a forked version of jsx.js to load JSX files with “.jsx” extension
* Rename all JSX files from “.js” to “.jsx”
* Copy non-JSX files rather than run them through the `jsx` command,
  which does unnecessary parsing
Stop gzipping until Chaos can serve compressed

The build is creating a gzipped version of the JS, but Chaos does not
handle gzipped assets. Stop doing the work until the file is used.
Merge pull request #320 from mesosphere/compile-only-jsx

Compile only JSX assets
Make `<hr>` and .form-control higher contrast

With light on a screen, the contrast is too low to see the form fields.
Add a small amount of contrast to aid.
Enforce valid hostnames (minus uppercase) for app IDs

Marathon’s modified hostnames allow digits, dashes, dots, and lowercase
letters. Normal hostnames allow uppercase letters and are case
insensitive, but that would likely be awkward in Marathon's app naming.
Document app ID requirements in REST.md

App IDs must match `/^[a-z0-9.-]+$/` currently, and that should be
documented.

Fixes #314.