add notes about contributing via desired features

Contributors can be helpful by doing the features we have greenlit.
add an options argument to parseXml so that xmlParserOptions can be passed to xmllib's underlying XML parsing function

The options argument, if provided, is an object whose keys correspond
to flags defined in xml_document.cc. If the corresponding value of the
key is true (or true-like), the flag xmlParserOption flag gets passed
to xmlReadMemory.

Example:

    libxmljs.parseXml(xml, {noblanks: true});

which is particularly useful when calling toString() to produce formatted
output on the document later. If you parse an XML string that has indentation,
insert some nodes, and then try toString() on it, it won't indent the new
nodes properly unless `noblanks` is set in the options.

See:
http://xmlsoft.org/html/libxml-parser.html#xmlParserOption
tests for parseXml options
Merge pull request #225 from JoshData/parseXml_options_argument

add an options argument to parseXml
0.9.0
Comments: Add initial support and tests

 * This commit makes it possible to create
   XML commment nodes in nodejs.
 * A new XmlComment class is introduced
   which exports a method text() to get and set
   the comment content.
 * This patch also includes tests to assert comment
   creation and the getting and setting of comment
   content through the text() function.
Merge pull request #229 from lanoxx/master

Comments: Add initial support and tests
Use NAN 1.1.2

Node 0.11+ uses a version of v8 which has radically changed APIs. NAN is
a project to support legacy and currency versions of the v8 apis.
lock down nodeunit devDep
0.10.0
Added property validationError to XML document after calling XmlDocument::Validate.

This gives an ability to see validation error when validating XML with an XSD.

Conflicts:
	src/xml_document.cc
Covered generation of validationErrors with tests
Remove /docs - documentation lives on the wiki
fix bad merge of xml validation - use NAN to make strings
drop support for node 0.6.x
0.11.0
render libxmljs and its bundled libxml libs usable in other addons
README: use svg badge

[ci skip]
0.11.1
basic doctype binding