add "db_prefix" option for MySQL
set MyISAM as engine for 'tags' table
fix reddit error with undefined favIconUrl property
Merge pull request #389 from bbeardsley/master

fix reddit error with undefined favIconUrl property
Merge pull request #390 from kucoe/master

Allow entry share to be configured
Merge pull request #391 from mistic100/master

Add table prefix parameter for MySQL engine
update docs and version