remove redundant activity filter text, fixes #31

that is, boonebgorges/bp-groupblog#31
Readme
Update pot for 1.8.8
Bump version numbers to 1.8.8
Merge branch '1.8.x'
Merge branch 'master' of https://github.com/boonebgorges/bp-groupblog
allow <em> and <strong> in group blog post title activities