fixes issue with query string parsing when a z exists

closes #127

lib/postal/query_string.rb

@@ -14,7 +14,7 @@ def empty?
     end
 
     def to_hash
-      @hash ||= @string.scan(/([a-z]+)\:\s*(?:(\d{2,4}\-\d{2}-\d{2}\s\d{2}\:\d{2})|\"(.*?)\"|(.*?))[\s\z]/).each_with_object({}) do |(key, date, string_with_spaces, value), hash|
+      @hash ||= @string.scan(/([a-z]+)\:\s*(?:(\d{2,4}\-\d{2}-\d{2}\s\d{2}\:\d{2})|\"(.*?)\"|(.*?))(\s|\z)/).each_with_object({}) do |(key, date, string_with_spaces, value), hash|
         if date
           actual_value = date
         elsif string_with_spaces

spec/lib/postal/query_string_spec.rb

@@ -0,0 +1,45 @@
+require 'rails_helper'
+
+describe Postal::QueryString do
+
+  it "should work with a single item" do
+    qs = Postal::QueryString.new("to: test@example.com")
+    expect(qs.to_hash['to']).to eq 'test@example.com'
+  end
+
+
+  it "should work with a multiple items" do
+    qs = Postal::QueryString.new("to: test@example.com from: another@example.com")
+    expect(qs.to_hash['to']).to eq 'test@example.com'
+    expect(qs.to_hash['from']).to eq 'another@example.com'
+  end
+
+  it "should not require a space after the field name" do
+    qs = Postal::QueryString.new("to:test@example.com from:another@example.com")
+    expect(qs.to_hash['to']).to eq 'test@example.com'
+    expect(qs.to_hash['from']).to eq 'another@example.com'
+  end
+
+  it "should return nil when it receives blank" do
+    qs = Postal::QueryString.new("to:[blank]")
+    expect(qs.to_hash['to']).to eq nil
+  end
+
+  it "should handle dates with spaces" do
+    qs = Postal::QueryString.new("date: 2017-02-12 15:20")
+    expect(qs.to_hash['date']).to eq("2017-02-12 15:20")
+  end
+
+  it "should return an array for multiple items" do
+    qs = Postal::QueryString.new("to: test@example.com to: another@example.com")
+    expect(qs.to_hash['to']).to be_a(Array)
+    expect(qs.to_hash['to'][0]).to eq 'test@example.com'
+    expect(qs.to_hash['to'][1]).to eq 'another@example.com'
+  end
+
+  it "should work with a z in the string" do
+    qs = Postal::QueryString.new("to: testaz@example.com")
+    expect(qs.to_hash['to']).to eq "testaz@example.com"
+  end
+
+end