add woothemes_features_image_size filter
- Adds "woothemes_features_single_slug" as a filter for the single feature URL slug
- Adds "woothemes_features_archive_slug" as a filter for the features archive URL slug
- Adds a flush_rewrite_rules() call on plugin activation
Merge pull request #27 from woothemes/url-slug-filters

Adds URL slug filters.
icon. closes #31
default args filterable. closes #30
Adds a setting to only link feature titles if they have a custom URL set. Closes #22.
Adds %%PERMALINK%% template tag. Closes #6.
Adjusts the 'id' parameter to cater for multiple ID values.
Adjusts the 'id' parameter to cater for multiple ID values. Closes #24.
Updates readme file for the 1.4.0 release.
Merge pull request #32 from woothemes/release-1-4-0

Release 1 4 0