Detect the libkakasi file name in a more reliable way.

Give up using the LIBRUBY_SO value as a hint in favor of borrowing
ruby-ffi's map_library_name method.
Add .travis.yml.
2014
Add a task "compile".
Run rake compile before test.
Install libkakasi.
Be more aggressive about the library search path.

- Always try libdir
- Then /lib and /usr/lib on Unix like systems
- And try a bare library file name
Capture LoadError.
Add development dependency on test-unit for ruby trunk.
Fix FFI detection for Rubinius.
Now CI passes with rbx-2.
Bump version to 1.0.1.