Merge pull request jenkinsci#30 from rchougule/proxy_from_env_vars

Proxy from multiple sources with priority. Custom Local Identifier fix

[maven-release-plugin] copy for tag browserstack-integration-1.1.5

[maven-release-plugin] copy for tag browserstack-integration-1.1.4

[maven-release-plugin] copy for tag browserstack-integration-1.1.3

[maven-release-plugin] copy for tag browserstack-integration-1.1.2

[maven-release-plugin] copy for tag browserstack-integration-1.1.1