Fix spelling mistake in errors

lib/holidays.rb

@@ -41,7 +41,7 @@ require 'date'
 #   Holidays.between(from, to, :ca_bc, :informal)
 module Holidays
   # Exception thrown when an unknown region is requested.
-  class UnkownRegionError < ArgumentError; end
+  class UnknownRegionError < ArgumentError; end
 
   VERSION = '0.9.2'
 
@@ -257,7 +257,7 @@ private
 
     regions.flatten!
 
-    raise UnkownRegionError unless regions.all? { |r| r == :any or @@regions.include?(r) }
+    raise UnknownRegionError unless regions.all? { |r| r == :any or @@regions.include?(r) }
 
     regions
   end

test/test_holidays.rb

@@ -31,15 +31,15 @@ class HolidaysTests < Test::Unit::TestCase
   end
 
   def test_requires_valid_regions
-    assert_raises Holidays::UnkownRegionError do
+    assert_raises Holidays::UnknownRegionError do
       Holidays.on(Date.civil(2008,1,1), :xx)
     end
 
-    assert_raises Holidays::UnkownRegionError do
+    assert_raises Holidays::UnknownRegionError do
       Holidays.on(Date.civil(2008,1,1), [:ca,:xx])
     end
 
-    assert_raises Holidays::UnkownRegionError do
+    assert_raises Holidays::UnknownRegionError do
       Holidays.between(Date.civil(2008,1,1), Date.civil(2008,12,31), [:ca,:xx])
     end
   end