Edited Issue: Build_iOS: add .gitignore [373]

Hi,

in Build_iOS folder, shouln't we add a .gitignore file, so as not to pollute our git status; e.g.

boostoniphone/
boost.framework/
build.ios/
ios-cmake/
openssl/
OpenSSL-for-iPhone/

(Other option would be to add above repositories as Git submodules)
I added build.ios/ folder as well, since it gets created by ./configure.sh

Kind Regards,
Julien