Set ONLY_ACTIVE_ARCH to NO even for Debug configuration. This leads to c...

...ompile time warning in Xcode but removes problems in complex projects with different libraries when some of the libraries don't support new arm64 architecture and therefore you have to compile whole project for armv7.

Removed unnecessary ARCHS definition as it is derived automatically from SDKROOT. Set SDKROOT to iphoneos instead of iphoneos7.0 in order to automatically pick correct present SDK.