Synchronizator can disable member using authoritativeGroup attribute

- create new authoritativeGroup attribute module
- change synchronizator code to work with authoritativeGroup attribute

--- NEED TO BE DONE AFTER MERGE THIS COMMIT ---
1] create new attribute authoritativeGroup
2] set rights for this new attribute
 - WRITE = GroupManager, VoManager
 - READ  = VoManager
SPRING: Fixed Spring version used in xsd URL

- Use version-less URL for Spring xsd validators.
- Set version 3.1 in manually added spring.handlers and spring.schemas.
- Removed many unused or duplicite context definitions.

Now correct mapping should be provided by Spring libraries, which maps
URLs to classpath.
Fixed Maven plugin execution for Eclipse

- Added lifecycle mapping for serviceloader plugin.
Updated project info in pom.xml
Do not set versions on plugins and dependencies in child projects

...because they are inherited from main project pom.xml

- Removed ant-run maven plugin lifecycle mapping for Eclipse,
  since plugin is not used by any of our modules.
Merge pull request #388 from zlamalp/eclipse

Update project pom.xml

- Added lifecycle mapping for serviceloader plugin (for Eclipse).
- Removed lifecycle mapping for ant-run plugin (for Eclipse). It's not used anymore.
- Removed explicit version definition in child pom.xml since versions are inherited from parent.
- Updated project info in main pom.xml.
Merge pull request #387 from zlamalp/spring

SPRING: Fixed Spring version used in xsd URL

- Use version-less URL for Spring xsd validators.
- Set version 3.1 in manually added spring.handlers and spring.schemas.
- Removed many unused or duplicite context definitions.
Updated .gitignore

- Ignore also dependency-reduced-pom.xml which is created in
  perun-core root folder by maven-shade-plugin.
Merge pull request #391 from zlamalp/gitignore

Updated .gitignore
WEB: removed perun-web from public repo

- Web presentation was moved to our private repository with it's new version
Merge pull request #392 from zlamalp/noweb

WEB: removed perun-web from public repo
Merge pull request #374 from stavamichal/synchronizatorCanRemovePeopleFromVo

Synchronizator can disable member using authoritativeGroup attribute