TEIIDDES-1739 DDL Importer modifications
Merge pull request #190 from mdrillin/DdlImporterMods

TEIIDDES-1739 DDL Importer modifications
TEIIDDES-1771 Corrects DDL File combo box history
Merge pull request #191 from mdrillin/TEIIDDES-1771

TEIIDDES-1771 Corrects DDL File combo box history
TEIIDDES-1768: Replace exec calls to mvn with common utility macro

* Imports the mvn macro from the common build script. This macro tries to
  execute the correct command for the OS that the script is being run on

* scripts/build-common.xml
 * Defines the mvn macro for platform dependent execution
TEIIDDES-1731: Workaround for flat file connection wizard

* Fragment plugin that replaces the FolderSelectionWizardPage with a
  substitute page that supports a checkbox that can turn off the
  validity check on the folder path entry, allowing 'invalid' paths to be
  inputted.

* Not a perfect solution since the FolderPropertyPage (displayed for the
  properties of an existing connection) cannot be replaced.

* FlatFileStartupOverrider
 * Hacks into the UIManifestExplorer and uses reflection to replace the
   class specified for the wizard page.

* Long-term this should be removed in favour of an upstream eclipse
  datatools fix for this. See https://bugs.eclipse.org/bugs/show_bug.cgi?id=412278