Add data files for missing time zones from issue #16

This PR adds the 6 remaining time zones referenced in issue #16 based on updated time zone data.  Data used for this PR was obtained from http://www.iana.org/time-zones , specifically the Time Zone Data v. 2012j package.  

I did not attempt to update the entirety of the timezone gem data to match this latest update - I only addressed the time zones referenced in this issue.  So there may (and likely are) updates that need to be applied to the existing JSON files and/or additional JSON files that need to be created.  

That all said, the data from the package I used to create these JSON files is as follows:

```
# from file africa
Zone	Africa/Juba	2:06:24 -	LMT	1931
			2:00	Sudan	CA%sT	2000 Jan 15 12:00
			3:00	-	EAT

# from file backward
Link	America/Atikokan	America/Coral_Harbour

# from file backward
Link	America/Atikokan	America/Coral_Harbour

# from file northamerica
Zone America/Creston	-7:46:04 -	LMT	1884
			-7:00	-	MST	1916 Oct 1
			-8:00	-	PST	1918 Jun 2
			-7:00	-	MST

# from file southamerica
Link	America/Curacao	America/Lower_Princes # Sint Maarten
Link	America/Curacao	America/Kralendijk # Bonaire, Sint Estatius and Saba

# from file asia
Zone	Asia/Hebron	2:20:23	-	LMT	1900 Oct
			2:00	Zion	EET	1948 May 15
			2:00 EgyptAsia	EE%sT	1967 Jun  5
			2:00	Zion	I%sT	1996
			2:00	Jordan	EE%sT	1999
			2:00 Palestine	EE%sT	2008 Aug
			2:00 	1:00	EEST	2008 Sep
			2:00 Palestine	EE%sT	2011 Apr  1 12:01
			2:00	1:00	EEST	2011 Aug  1
			2:00	-	EET	2011 Aug 30
			2:00	1:00	EEST	2011 Sep 30 3:00
			2:00	-	EET	2012 Mar 30
			2:00	1:00	EEST	2012 Sep 21 1:00
			2:00	-	EET

```