Fix Cannot read property 'length' of null error
Fix Cannot read property 'length' of null error

Fix an error that has been introduced in commit 846e592c, that clears
the selectedOptions to clear all labels from the mutliselect, when
options and selectedOptions were cleared. selectedOptions should be an
empty array instead of null.

edcarroll/ng2-semantic-ui,mcosta74/ng2-semantic-ui,edcarroll/ng2-semantic-ui,mcosta74/ng2-semantic-ui