FIXED: Spelling mistake with the naming of the palette directive.
NEW-Enhanced:Palette now shows the node and link options icons in a list and a text indicator changes when an option is selected.
NEW: Palette selection service which will be used to store the
state of the currently selected palette option and to notify
the editor graph, when the user has selected a new option.

DOC-FIXED: Improved the clarity of the attributes panel documentation.

FIXED: Editor-graph does not the default testing schemes anymore.
ENHANCED-LOOKS: of attributes panel. Now shows a form specific for
the node/ link type when it is selected.
ENHANCED-LOOKS: The editor graph, adding nodes/links controll scheme
now relies on the palette options. Links are now added by left clicking
on the source node and then left clicking on the target node.
ENHANCED-LOOKS: The appropriate symbols for the app properties and
screenNode now appear on the graph when those node types are created.
TODO: Implement the visuals for the ScreenTransitionLink
ENHANCED-LOOKS: ScreenTransitionLink is now represented using a dashed
 line and arrow head (as outlined in the solution description document).
ENHANCED-LOOKS: Screen node's icon is now determined based the isTab and
API domain attribute and will change when these attributes are changed.
FIXED-LOOKS: bug where the App Properties node was being changed to nonsense
when the icon attribute was being filled in. Now the label on the visual
model remains constant, i.e., will continue to show the text  "App Properties"
regardless of the attributes state.
FIXED: Bug where the isLanding attributes data was not being sent to the server.
Merge pull request #11 from rlgod/feat/Palette-Options-Selection

Feat/palette options selection