Log Message:
Update skf to 1.99.7.

skf (1.99.7)

  * ruby 2.1.0 support
  * fix bug in MIME encoding under early_mime_out mode
  * further nkf-compatibility
  * trim some terminal sequence sweep behaviors
  * UnicodeData undated to 6.3
  * fix nkf compatible option --cp932 behavior
  * fix some bugs