v1.3 Enhancements

* Added $xsbf_theme_option to control displaying the custom header
below the navbar. Removed content-header.php and header.php as those
are no longer needed because the parent theme handles this now.
* Added new custom header image of a desktop with briefcase
* Added new custom header image of a city skyline
* Changed sample comment form in footer to not require Jetpack. This
was displaying as ugly shortcodes in theme preview.
* Bumped version numbers.
* Includes all the latest enhancements from the parent theme, such as
support for portfolios and testimonials, new page templates, full-width
embedded videos, expanded color palette, and much more.