Add Gem spec

Signed-off-by: Lennart Fridén <lennart@devl.se>
Ignore built gems.

Signed-off-by: Lennart Fridén <lennart@devl.se>
Ruby 1.9 UTF-8 compatibility fix.

Fixes https://github.com/bleything/plist/issues/15

Signed-off-by: Lennart Fridén <lennart@devl.se>
Bump version to 3.1.1.

Signed-off-by: Lennart Fridén <lennart@devl.se>