Run price & earnings through utf8_encode

This fixes the following notices -

Notice: iconv() [function.iconv]: Detected an illegal character in input string in /wp-content/plugins/easy-digital-downloads/includes/admin/reporting/pdf-reports.php on line 113

Notice: iconv() [function.iconv]: Detected an illegal character in input string in /wp-content/plugins/easy-digital-downloads/includes/admin/reporting/pdf-reports.php on line 114
Merge pull request #2266 from elliott-stocks/patch-22

Run price & earnings through utf8_encode
removed double comma
Merge pull request #2275 from nextgenthemes/patch-1

removed double comma
Fixed metabox.php - was pre-echoing an argument to an apply_filter

Was echoing an argument to an apply_filter (via _e) rather than echoing the result of the apply_filter (with its argument submitted via __).
Merge pull request #2284 from danlester/master

Fixed metabox.php - was pre-echoing an argument to an apply_filter
Update .travis.yml
Merge branch 'master' into release/2.0