differentiate data drive from a boot drive

a data drive does not have the image_type attribute
Update DataDriveSupport.java
differentiate boot drive from a data drive

boot drive will have an image_type attribute
release ip bug fix

check for null json object when releasing ip
os icon and ip bug fix

ogbugz 2899 - os icon not displayed for servers.
api 2.0 changed w/regards server ip details so implementation updated
to parse the new object
attach volume big fix FB2017

cloudsigma now only allow up to 4 units per controller
Merge pull request #3 from daniellemayne/develop

bug fixes and code tidy up