Increase graph fluidity + update/refactor scaling code

Remove cursor circle outline since it was not updating correctly when
outside svg area.

Add functionality to scale node icons and links using slider. Also
rename slider from zoom to scale (was not a true zoom, objects stayed
in place).

Introduce new k-value heuristic used to pick appropriate charge and
gravity values based on graph density.
Graphs generated based on k-value look and feel much more fluid than
before. Idea by mbostock on Stack Overflow.

Misc. refactors
  -function resize() moved to be next to slider javascript
  -added BASE_VALUE constant for slider default and for
calculating scaling factor
  -force layout initialization in two separate places combined
Add icons for each type of element

Add code to display icons for each unique type
Icons are found in resources/ and are from Cisco network topology icons
which are free to use but cannot be modified

Delete test.html and move all code to display.html
Add namespace prefix constants to clean up code

Define refs, ref, xsd, owl, mml, and mrs namespace prefix constants to
make code easier to read.
More code cleanup, rename image to icon

Define ICON_PATH constant for maintainability in case resources/ folder
is later subdivided into resources/icons/.

References to 'image' replaced with 'icon' to be more specific.

Code block for determining icon path converted from nested switches
into self-executing anonymous function, which reduces code length by
2/3rds.
Fix small problems with icons and parser

Add code and image for missing POSIX_IOBenchmark type icon

Fix typo on block_storage_system.jpg -> block_storage_service.jpg

Add jena jar to WEB-INF/lib and remove from pom.xml.
Merge pull request #2 from AffineHat/master

Add support for icons + finished slider functionality + improved graph fluidity