replaced 3 if-not-blank checks with if-present checks (#2230)

* replaced if-not-blank with if-present

an instance of code was testing presence via `!a.blank?`. this is now
replaced with a more readable version: `a.present?`

* replaced 2 if-not-blank checks with if-present checks

* temporarily restrict travis

* reverted travis changes

* readded whitespace

lib/paperclip/attachment.rb

@@ -349,7 +349,7 @@ module Paperclip
 
     # Returns true if a file has been assigned.
     def file?
-      !original_filename.blank?
+      original_filename.present?
     end
 
     alias :present? :file?

lib/tasks/paperclip.rake

@@ -18,7 +18,7 @@ module Paperclip
         raise "Class #{klass.name} has no attachments specified"
       end
 
-      if !name.blank? && attachment_names.map(&:to_s).include?(name.to_s)
+      if name.present? && attachment_names.map(&:to_s).include?(name.to_s)
         [ name ]
       else
         attachment_names

spec/paperclip/attachment_spec.rb

@@ -1121,7 +1121,7 @@ describe Paperclip::Attachment do
     context "with a file assigned but not saved yet" do
       it "clears out any attached files" do
         @attachment.assign(@file)
-        assert !@attachment.queued_for_write.blank?
+        assert @attachment.queued_for_write.present?
         @attachment.clear
         assert @attachment.queued_for_write.blank?
       end