Fix for Issue #8

Added a Custom Content Pane where we can change the icon/title of the
selected tab.

Added ReferenceCustomTabComponent which packs the tab title and icon
into a component.
fixed typos and removed tab iconLabel

componenet -> component
hideableComponentWraper -> hideableComponentWrapper

setting icon to the titleLabel itself instead of creating a new label
and adding the icon.
changed constructor of DemoTabContentPane

passing instance of ReferenceCustomTabComponent instead of TabManager to
the constructor DemoTabContentPane
ReferenceCustomTabComponent inherits from JLabel instead of JPanel
Merge pull request #24 from chetankothari/fix-issue8

Ability to change icon and title. Closes #8