some image processing fixes; try to download only if the src attribute is not empty

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9465 5f5364db-9458-4db8-a492-e30667be6df6
ie11 progress

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9466 5f5364db-9458-4db8-a492-e30667be6df6
ie11 test fixes

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9467 5f5364db-9458-4db8-a492-e30667be6df6
forgotten change comment

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9468 5f5364db-9458-4db8-a492-e30667be6df6
force build

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9469 5f5364db-9458-4db8-a492-e30667be6df6
force build

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9470 5f5364db-9458-4db8-a492-e30667be6df6
pom.xml: update maven-jar-plugin to 2.5

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9471 5f5364db-9458-4db8-a492-e30667be6df6