Cleanup NetBeans license header for module css.prep

[emilianbold]

Review and cleanup the license header in css.prep

Oracle donated NetBeans to the Apache Software Foundation.

Your task now is to replace the old license header that has Oracle (and/or Sun Microsystems
and/or NetBeans) in it with the standard Apache Software Foundation license header.

For an empty file that supports headers you must add the Apache license header.

Note that you have to use the proper license header for Java, .properties or HTML files.
Look at the nearby files for templates and copy-paste the license header.

When done commit the changes with a commit message that starts with first line
"[NETBEANS-54] Module Review " and a message body describing your review.

See a longer explanation about what we are doing here: https://cwiki.apache.org/confluence/display/NETBEANS/List+of+Modules+to+Review

Please announce in a comment when you have started work.

Files that need to be looked at in css.prep:

css.prep/src/org/netbeans/modules/css/prep/ui/resources/style.less
css.prep/src/org/netbeans/modules/css/prep/ui/resources/style.scss
css.prep/test/qa-functional/data/css_prep/public_html/cc.less
css.prep/test/qa-functional/data/css_prep/public_html/cc.scss
css.prep/test/qa-functional/data/css_prep/public_html/folder/part.scss
css.prep/test/qa-functional/data/css_prep/public_html/folder/partial.less
css.prep/test/qa-functional/data/css_prep/public_html/less_syntax.less
css.prep/test/qa-functional/data/css_prep/public_html/sass_syntax.scss
css.prep/test/unit/data/testFiles/test.less
css.prep/test/unit/data/testFiles/testIssue227676.scss
css.prep/test/unit/data/testProject/public_html/client1.scss
css.prep/test/unit/data/testProject/public_html/lib1.scss
css.prep/test/unit/data/testProject/public_html/test.less
css.prep/test/unit/data/testProject/public_html/test1.scss
css.prep/test/unit/data/testProject/public_html/test2.scss

[tomazst]

I'll take this!