LRDOCS-1306 Copy Markeplace content from devGuide, adjust header levels, and commit supporting files.
LRDOCS-1306 Edit the Marketplace Developer's Guide content and replace tip image file.
Update MP Dev Guide's links to use /discover/portal
Merge branch 'lrdocs-1306-mp-dev-guide' of git://github.com/jhinkey/liferay-docs into wordsmithing
Wordsmithing.
Wordsmithing.
Wordsmithing.
Wordsmithing.
Merge branch 'wordsmithing'