Revert "TAP5-2197: the previous fix didn't cover the situations in which <style>"

This reverts commit e445821bf89e4dbae11c97e93c04a1438ce736df.

Conflicts:
	tapestry-core/src/test/groovy/org/apache/tapestry5/integration/app1/StylesheetPlacementTests.groovy
TAP5-2197: When importing a stylesheet, import the base stack
Add additional comments to @Import annotation
Advance version number to 5.4-beta-3