podspec bumped to 3.2.1

fixed aztec decoder rawBytes (zxingify#291)

* fixed aztec decoder rawBytes
* changed flag to display rawBytes as hex

Version bump: 3.1.0

Version bump: 3.0.4

Version bump: 3.0.3

Version bump: 3.0.2

Version bump: 3.0.1

Version bump: 3.0.0

Version bump: 2.2.8

Organize into subspecs