Fix headers/footers in landscape mode.

Now you need to set a "is_landscape:1" line in your header and footer CSS in addition
to "size:a4 landscape" in the @page frame.
Quick fix to limit reportlab version range.

Version 3.0, if installed, will not be detected by xhtml2pdf, so define the reportlab dependency as a range (>=2.2, <3.0).
Merge pull request #157 from amcgregor/master

Quick fix to limit reportlab version range.
Merge pull request #155 from gthb/fix-header-footer-in-landscape-mode

Fix headers/footers in landscape mode.