Add utf-8-mac conversion to get_vimfiler_candidates

Only Mac iconv can convert utf-8-mac to some encoding.
- Updated vital.
Merge pull request #336 from joker1007/get_vimfiler_candidates_utf-8-mac

Add utf-8-mac conversion to get_vimfiler_candidates
- Refactorred for utf-8 mac.
- Improved buffer name prefix.
Improved utf-8-mac conversion
Merge pull request #338 from todashuta/utf-8-mac

Improved utf-8-mac conversion.
- Updated vital.
- Improved redraw_hold_candidates value.
- Fixed #339 undo source.
- Fixed undo source.
- Updated FAQ.
- Added g:unite_ignore_source_files.
- Improved documentation.
Wording change for error messages

I think this wording is a little better, but if we prefer to keep the old wording, we should correct the spelling of "attention".
Merge pull request #342 from oconnor663/patch-1

Wording change for error messages
- Fixed #341 g:unite_ignore_source_files.
- Fixed #340 auto-resize behavior.
- Fixed unite buffer name.
- Deleted :NeoComplCacheLock.