limited amount of threads for @Async

See #127, release log:

• 56830f9 by @null: Fixed Java-8-related build problem. Ignored a failing test.
• 1f2ad5b by @null: #123 - fixed copyright section
• 35a44a0 by @null: simplified
• 7df838c by @null: maven opts fix
• b90201a by @null: opts fixed
• c84d073 by @null: cache .m2
• 5a54ed6 by @null: path fix
• f1fc53a by @null: zipfile
• e6f69f8 by @null: sub-dir
• 8872f31 by @null: shorter DIR
• 5a571ab by @null: echo
• 88841f5 by @null: dir again
• d098362 by @null: dir
• a8c465c by @null: mkdir
• 1243942 by @null: typo in ps
• 050ddda by @null: download maven and unzip
• 332aa25 by @null: only 1.7 for appveyor
• d29effa by @null: appveyor simplified
• abff7a7 by @null: appveyor cfg
• 6773d0a by @null: version fix
• d160d5c by @null: version number
• b7a5c8c by @null: appveyor
• cd4c871 by @null: arch
• 6c7fc33 by @null: #118 fixed checkstyle violations
• 8e847cd by @null: #118 fixed CyclomaticComplexity
• af15608 by @null: #118 added check for immutability for actual classes in addition to declared
• 2225e9a by @null: #118 added check for immutability for actual classes in addition to declared
• 23ccd22 by @null: #118 added check for immutability for actual classes in addition to declared
• 1a1c373 by @null: Merge branch 'master' into 107

Conflicts:
src/site/apt/annotation-loggable.apt.vm

• d07d399 by @null: Merge remote branch 'fork/108'
• 90ad7c6 by @null: Merge remote branch 'fork/109'
• 95792e3 by @null: #107 fixes after review
• 345180a by @null: #111 extracted methods
• d8d16ca by @null: #109 added handling of return types: byte[] and short[]
• 73f27d4 by @null: #108 added docs for 'precision' param of @loggable
• c2e03aa by @null: #107 added documentation for 'name' param in @loggable
• df931c3 by @null: parent 1.16

Released by Rultor 2.0-SNAPSHOT, see build log