Correct use of asterisk in docs.
Updated ITK build instructions

Changed the ITK build and usage instructions to reflect that a SCIFIO
ImageIO plugin can now be automatically fetched by the latest ITK
builds.
Merge pull request #552 from bpindelski/rebased/dev_4_4/asterisk

Correct use of asterisk in docs. (rebased onto dev_4_4)
Merge pull request #554 from hinerm/itk_dirs_dev_4_4

Updated ITK build instructions (rebased on dev_4_4)