refactor(distro): use default linux browser if configured

- use environment variable BROWSER if already set
- use gnome or X default browser if configured
- refactor browser executable search to be more extensible
- use echo -e option to enable interpretation of backslash escapes
  (most distributions disable this by default)
- remove redundant spaces
fix(start-camunda): add google chrome to browser selection
merge(start-script): add better browser handling

merges Pull Request #53

Conflicts:
	distro/gf31/assembly/src/start-camunda.sh
	distro/jbossas7/assembly/src/start-camunda.sh
	distro/tomcat/assembly/src/start-camunda.sh
delete(engine-ws): remove deprecated WebService implementation

The incomplete and deprecated implemetation of WebServices is deleted from
the core engine.

closes CAM-1603
delete(drools): remove drools from core engine

The drools dependencies and unsupported code is removed from core engine.

closes CAM-1602
Merge branch 'master' of github.com:camunda/camunda-bpm-platform
chore(callActivity/Expression): Improve REGEX for calledElement

related to CAM-1490
chore(cdi/jsf/test): Provide test case for right bean resolving

related to CAM-1609