1.2.0

Enhancements

• Only create shims for swift* and lldb* binaries found within Xcode installs. Before we created shims for all executable tools found in Xcode and created shims for tools like ctags, cc, clang, etc.
• Adds support for installing binary GM releases.

Bug Fixes

• Expose not found errors when using swiftenv exec against unknown commands.
• Swift preview versions such as 3.0-preview-1 will be detected as binary versions when using swiftenv install.