Configurable timeouts, retries and backoffs

travis build#134

Features

• Configurable timeout, retries and backoff on http requests towards bitbucket

Checksums

File	Checksum (sha256)
bitbucket_server_cli-linux.tgz	16aef193645a763a7e48ca9875dbd01ef0272ba836864e41c806fa0ce5d4d7d2
bitbucket_server_cli-osx.tgz	b6c0c4f4631c34f33afbb7a883e00dbf21562a6ffd83cfc15e9ad7d4c69db504
bitbucket_server_cli-windows.tgz	34ae76a5ebbdcd3fa31c0bfc1fed3d941cc9a52a8b2c5734778c59132daa65aa