Wrote comment.
Getting the toplevel corpus from the staging area failed, when there exists
subcorpora.

closes #254
Merge remote-tracking branch 'korpling/annis/develop' into develop
updating to Vaadin 7.1.8 that fixes some push fixes among others
Corpus import returns a wrapper class, which collect all exceptions, so the
business logic can decide later, which and when excecptions of the import
process are exposed. The kickstarter currently shows the last thrown execption.

closes #253
change return type of importCorporaSave()
Merged 'develop'.

Conflicts:
	annis-kickstarter/src/main/java/de/hu_berlin/german/korpling/annis/kickstarter/ImportDialog.java
	annis-service/src/main/java/annis/administration/CorpusAdministration.java
	annis-service/src/main/java/annis/service/internal/ImportWorker.java
introducing an alias REST function to query corpora by their alias names
use more general REST function to get the corpus information (AnnisCorpus object) and for a corpus and/or alias