Error trying to reinstall rugged gem

I'm trying to reinstall rugged as it's causing issues with another program (Dandelion Deploy).

I've recently updated my RVM and Ruby, and installed cmake and pkg-config again, but I get this error when I run the following command: gem install rugged

Fetching: rugged-0.22.2.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing rugged:
    ERROR: Failed to build gem native extension.

    /Users/J/.rvm/rubies/ruby-2.0.0-p645/bin/ruby -r ./siteconf20150605-56781-qfplzm.rb extconf.rb
checking for gmake... no
checking for make... yes
checking for cmake... yes
checking for pkg-config... yes
 -- cmake .. -DBUILD_CLAR=OFF -DTHREADSAFE=ON -DBUILD_SHARED_LIBS=OFF -DCMAKE_C_FLAGS=-fPIC -DCMAKE_BUILD_TYPE=RelWithDebInfo -G "Unix Makefiles"
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
    --with-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/Users/J/.rvm/rubies/ruby-2.0.0-p645/bin/ruby
    --use-system-libraries
extconf.rb:13:in `sys': ERROR: 'cmake .. -DBUILD_CLAR=OFF -DTHREADSAFE=ON -DBUILD_SHARED_LIBS=OFF -DCMAKE_C_FLAGS=-fPIC -DCMAKE_BUILD_TYPE=RelWithDebInfo -G "Unix Makefiles"' failed (RuntimeError)
    from extconf.rb:66:in `block (2 levels) in <main>'
    from extconf.rb:65:in `chdir'
    from extconf.rb:65:in `block in <main>'
    from extconf.rb:62:in `chdir'
    from extconf.rb:62:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in /Users/J/.rvm/rubies/ruby-2.0.0-p645/lib/ruby/gems/2.0.0/gems/rugged-0.22.2 for inspection.
Results logged to /Users/J/.rvm/rubies/ruby-2.0.0-p645/lib/ruby/gems/2.0.0/extensions/x86_64-darwin-11/2.0.0/rugged-0.22.2/gem_make.out

I'm a frontender, so this is way out of my comfort zone. Any help appreciated!

Mac OSX 10.7.5, Lion

Solved it.

I installed the latest version of XCode I could (4.6.3) on OSX 10.7.5.

To get dandelion working, I installed the following gems: rugged, dandelion and net-sftp

and everything worked again.