Made calls to 'blank?' and 'present?' easier to reason about

Made calls to `blank?` and `present?` easier to reason about by changing code that did not need to be negative or double negative. It's just easier to think about code that's written in a positive way than negative code.

* Replaced `unless blank?` with `if present?`
* Replaced `reject(&:blank?)` with `select(&:present?)`
* Replaced `!blank?` with `present?`
* Replaced `!include?` with `exclude?`