Fixed Markup import. Modified get_partial() function which failed on some HTML

[eanon]

• Fixed Markup import.
• Modified get_partial() function (now relying on lxml) which failed parsing some pieces of HTML (didn't locate the modal body giving a partial that started at beginning of modal window until the end of the html document; ie. ).
• Added lxml as required dependency in setup.py.
• Removed any version constraint in requirements.txt of the examples. ­ Feel free to review at your convenience.