#19, #20 added DbSystem parameter to schema mapping
#19 #20 added system field in schema documentation
#19, #20 added sql testing algorithm
Merge branch 'master' into DbSystem-configuration
Merge branch 'master' into DbSystem-configuration

Conflicts:
	backend/src/main/java/de/uni_potsdam/hpi/metanome/results_db/DatabaseConnection.java
Added DB System field to frontend.
Change DataSourcePage Layout from FlowPanel to TabLayoutPanel
Refactor data source pages
Refactoring data source page: Add tests.
Merge branch 'DbSystem-configuration' into refactor_data_source_page

Conflicts:
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/DataSourcePage.java
Merge branch 'master' into refactor_data_source_page

Conflicts:
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/DataSourcePage.java
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/FileInputEditForm.java
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/input_fields/CsvFileInput.java
Add missing DBSystem and change identifier of database connections in listbox.
Merge branch 'master' into refactor_data_source_page

Conflicts:
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/DataSourcePage.java
A database connection can only be deleted if there is no reference from a table input.
Merge branch 'master' into refactor_data_source_page

Conflicts:
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/DataSourcePage.java
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/FileInputEditForm.java
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/TableInputEditForm.java
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/input_fields/CsvFileInput.java
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/input_fields/ListBoxInput.java
	frontend/src/main/java/de/uni_potsdam/hpi/metanome/frontend/client/input_fields/SqlIteratorInput.java
	frontend/src/test/java/de/uni_potsdam/hpi/metanome/frontend/client/TestHelper.java
	frontend/src/test/java/de/uni_potsdam/hpi/metanome/frontend/client/datasources/GwtTestDataSourcePage.java
Merge pull request #192 from HPI-Information-Systems/refactor_data_source_page

Refactor data source page