xpath with namespaces:

- xpath can not handle explicit namespaces, only abbreviations
  accompanied with namespace mapping dictionary
- allowing "{namespace}tagname" in xpath expressions by
  - replacing explicit namespaces with (generic) abbreviations
  - constructing a mapping accordingly
map default namespace of root node for xpath
fix a problem in comparing plain/unicode strings
Added tests to the xpath namespace fix.

Also some PEP8 and formatting fixes.
Merge branch 'master' into granular_authorization
Merge pull request #4 from krischer/master

XPath expressions can now handle namespaces
Allow cross origin requests.

Correctly respond to OPTIONS requests to allow cross origin
XMLHttpRequests. This should not affect security as authentication still
works as before.
Handle "multipart/form-data" content types.
Merge branch 'master' into granular_authorization

Conflicts:
	seishub/core/services/web.py
Merge pull request #5 from krischer/master

Cross origin requests and multipart/form-data content
formatResults() now works with nested dicts.

The db.util.formatResults() can now format nested dictionaries to XML.
The other formats and tests are still missing.
Added tests for the XML formatting.
Added tests for JSON formatting.

They are already passing. No changes are needed.
Setting HTTP content-tpye for xml response.

Also changed the docstring for the formatResults function.
Changes to the XHTML output.

It now also works with lists of dictionaries. It still works with the
previously returned proxy results. In the case of a list of
dictionaries, the order of the keys, will represent the table headers,
will be alphabetically.

Also changes the normalize_whitespace() helper function to a generic xml
whitespace normalization function.

Added two short XHTML output tests.
Added XHTML output tests.

Checks that missing fields are dealt with.
XHTML output now correctly handles missing fields.
Added two tests for XHTML output.

A tabular view is not quite suited for deeper data structures so this
should not be of much use but at least it works.
Adding util test to __init__
Merge branch 'master' into granular_authorization