Removed Merge Strategy

Prior to repackaging, there was path information and I used .gitattributes to
assign merge strategy=ours for the xmlproxy/__init__.py file.  That's no longer
necessary.
Added Ability to Accept Data from STDIN

By using the filename STDIN on the command line, blogtool now reads data from
the standard input.  Updated README.md with this as well.
Bug Fix- img Tags not closed properly

Awhile back, I'd modified the serializing of HTML string sent via XMLRPC.  I'd
changed it to use HTML methods in order to fix iframe tags, which weren't being
closed properly.

Unfortunately, this broke other HTML tags for XHTML like img tags.  This code
fix implements a serializer to convert an lxml tree into an HTML string.
Escape certain characters during GetPost

The lxml parser doesn't like certain characters unescaped, like the '&'.
Normally, the XMLRPC exchange causes these characters to be properly escaped,
for instance '&' as '&amp;'.  But there are certain instances where they are not
properly escaped.  We now search for the '&' characters in the text stream and
escape them prior to parsing.

Further, the `tostring` function provided by lxml will not convert the escaped
pattern back to their single character, i.e. change '&amp;' to '&'.  The code
properly handles this situation.

Note that we should probably eliminate all usage of the `tostring` function and
create our own serializer to deal with this situation.