let FileName use class perfix
let protobuf-objc supprot homebrew
let Protobuf-objc support cocoapods
remove no use options on use configure
add option to support file_name_prefix
hard code to let compiler don't gen ObjectivecDescriptor
fix bug on repeated not use initWithArray:
Merge branch 'develop'

Conflicts:
	Protobuf-objc.podspec
	src/compiler/objc_message_field.cc

Signed-off-by: Superbil <superbil@gmail.com>