refactor :stderr => :silence

replace with :print_stderr => false

The double test on options[:print_stderr] in system_command.rb
is intentional, and temporary.
recast :print => true as :print_stdout => true

in Cask::SystemCommand
remove :print_stdout => false

this is the default, and need not be specified
switch to %Q{} for complex quoting
Update RethinkDB to 1.15.0
Merge pull request #6336 from ndr-qef/rethinkdb

Update RethinkDB to 1.15.0
Upgrade Manico to 1.4.1
Merge pull request #6339 from crainiarc/manico

Upgrade Manico to 1.4.1
Upgrade torbrowser to v3.6.6
Merge pull request #6340 from joelpurra/torbrowser-3.6.6

Upgrade torbrowser to v3.6.6
re-use version in abgx360
re-use version in accessmenubarapps
re-use version in actprinter
re-use version in adapter
re-use version in adium
re-use version in adobe-digital-editions
re-use version in adobe-reader
re-use version in aegisub
re-use version in air-video-server
re-use version in airserver