supporting post request in print.pdf
removing duplicate + updating doc
corrections according review
Merge pull request #74 from procrastinatio/master

Adding POST support to print.pdf request
The key don't necessary exists in the opposite object.
Merge pull request #78 from sbrunner/fix-equals

The key don't necessary exists in the opposite object.
Fix protocole documentation

Highlight ``values``
Merge pull request #80 from sbrunner/fix-doc

Fix protocole documentation
Calculate the position of images taking account of the rotational offset
Merge pull request #82 from renumi/master

Calculate the position of images taking account of the rotational offset
Added placeholder for PdfUtils getimage.

This can address: https://github.com/mapfish/mapfish-print/issues/83. althoug it is a more general solution.