Cosmetic changes.
Use not tool/ but tools/. This is for naming consistency.
Move apps in gems to #{MRUBY_ROOT}/bin/ when apps is built for "host".
Merge pull request #1168 from monaka/pr-update-gem-application

Update gem application support.
Move mirb and mruby to mrbgems.
Add verbose mode to mirb
Merge pull request #1170 from h2so5/add-verbose-mode-to-mirb

Add verbose mode to mirb
rename mruby,mirb gems to mruby-bin-{mruby,mirb}
Merge branch 'monaka-pr-move-mirb-mruby-to-mrbgems'
Fix TypeError messages
Merge branch 'fix-type-error-message' of https://github.com/h2so5/mruby into h2so5-fix-type-error-message
string interpolation (#{foo}) does stringify implicitly; no need to call #to_s