Remove ć from gemspec to install in JRuby

JRuby 1.7.3 gives this error when installing: ERROR:  While executing gem ... (Psych::SyntaxError)
    (<unknown>): 'reader' unacceptable character '' (0x87) special characters are not allowed
in "'reader'", position 164 at line 0 column 0

Changed to 'c', built gem and installed just fine.