Add Cocoapods static_framework support

[soniccat]

I see Cocoapods RC (1.4.0.rc.1) supports swift static frameworks. Added that to avoid creating a dynamic library.
The latest Cocoapods RC can be installed using this command sudo gem install cocoapods --pre

[soniccat]

Replaced because of using NSNumber here. Had compile errors without that.

[staguer]

Hi @soniccat ! Can you please link me to some documentation for this static_framework flag?

Also, is this something that should be determined by those entities that import LayoutKit rather than by LayoutKit itself?

[soniccat]

@staguer hi, here it is http://blog.cocoapods.org/CocoaPods-1.4.0/ I see they have written it recently

can't say about dependencies, need to read the doc, it seems setting the flag should be enough, at least I've tested that it works

[nicksnyder]

Lgtm based on reading doc. Any downsides?

[chenxiao0228]

Enabling this will cause the binary to be linked statically.

If the pod consumer has multiple targets using LayoutKit, LayoutKit will be liked multiple times.

Agree with @staguer it might be more appropriate for the consumers to decide how it will be linked.

Cocoapods 1.5.0 is adding support for this use case, FYI.