php notices and method slug

Fixes php notices (WP_DEBUG):
Notice: Undefined offset: 1 in
/srv/www/wp-parser/public/wp-content/plugins/wp-parser/lib/class-plugin.
php on line 172

Notice: Undefined variable: post_data in
/srv/www/wp-parser/public/wp-content/plugins/wp-parser/lib/class-importe
r.php on line 326

Replaces double colons in method slugs with a dash before
sanitize_title() is used.
Merge pull request #107 from keesiemeijer/import-item

php notices and method slug
Import WP version
import WP version function
Merge pull request #108 from keesiemeijer/import-wp-version

Import wp version
update parsed data after import
updated date format for output
Merge pull request #109 from keesiemeijer/parse-data

update and output import data after import
Add wp_parser_pre_import_item filter
Add wp_parser_post_import_item action
Replace $data pre filter with a short-circuit filter.
Rename wp_parser_post_import_item filter to wp_parser_import_item to avoid 'post' ambiguity.
Merge pull request #113 from moderntribe/master

Hooks during item creation