Update template_data.json

There was a typo, updated to reflect what cisco shows on provisioning manual: http://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/csbpipp/ip_phones/administration/guide/SPA_500_admin.pdf
Update spa$mac.xml

Updates as per cisco standard on provisioning manual: http://www.voip4share.com/sources/Cisco_Small_Business_IP_Telephony_Provisioning_Guide.pdf
Fix Download picture tag, also fix Expansion Keys to accept a description
Merge pull request #163 from charlesrg/master

Update Background Picture tags to reflect cisco provisioning manual