fix #210
Add labeling demo. Fixes #315
Merge pull request #323 from patrickarlt/master

fix #210
added ImageServiceIdentifyTask

added spec to test default use case
added tests for ImageMapLayer.identify() factory method
added to karma files
renamed identify tasks to IdentifyFeatures and IdentifyImage
refactored common methods of identify tasks into Idenityfy.js
image identify requires geom sent as JSON, not x,y&sr=4326
added identify image example
added tests/props for mosaicRule, renderingRule, pixelSize
added api ref page for L.esri.Tasks.IdentifyImage