slightly decrease the overall font size.

- set font size on body to "smaller" (could also use a percentage or absolute size).  both "smaller" and a percentage respect the browsers default font settings, so if the user has customized this, it will be relative to their default font size (useful if the user has a hard time reading and has bumped up the font size).

- set table's font size to "inherit" (because many browsers override the font size of tables and do not inherit from parent content)

- removed explicit font-size values on a couple css rules

fixes issue #19
fixed issue #20 by doing a few things:
- now formatting .StixDescriptionValue the same way as .description.  This is now done in stix_to_html.xsl and is conditional on the stylesheet parameter "$enablePreformattedDescriptions"
- also removed the formatting that set the description to have a fixed width.  it will now resize with the parent table cell.

also addressed some margin/padding issues from issue #18
- in some browsers, the top level tables were overflowing their parent div.  this was caused by the margin being set and the width being 100%. the result was there was either no space or very small space on the right of these top level tables.