fix using wrong link to card.io sample in readme
Add fetch supported brands WPYTokenizer
Access publicKey through method instead of accessing
static variable directly
Use enum in place of magic number
Return json parse error from ErrorBuilder

ErrorBuilder returned only WebPay errors, and used
double pointer to return JSON build error.
Use ternary for existence checking of availability
Use bearer token in place of basic auth
Factor out shared procedure of NSMutableRequest to
templateRequest
Use consistent naming convention for private constants
Fix indent
Fix indent
Check if xctool is outdated before brew upgrade
Fix typo
Set accept language as requirement for every communication
Fix grammatical error
Rename 'Diners' to 'Diners Club'
Use extern constant card brand string in place of
literal string
Refer to self instead of class name
Replace card brand logos
Add small card brand logos