Graceful handling of regions which aren't CSS selectors

The dual use of regions (CSS selector and natural language name)
causes some difficulties in processing. Since the CSS selector
is tried first, we need to ensure the underlying logic
doesn't bail on invald selector syntax.

See #84

src/SilverStripe/BehatExtension/Context/SilverStripeContext.php

@@ -138,13 +138,17 @@ public function setRegionMap($regionMap){
 	 */
 	public function getRegionObj($region) {
 		// Try to find regions directly by CSS selector.
-		$regionObj = $this->getSession()->getPage()->find(
-			'css',
-			// Escape CSS selector
-			(false !== strpos($region, "'")) ? str_replace("'", "\'", $region) : $region
-		);
-		if($regionObj) {
-			return $regionObj;
+		try {
+			$regionObj = $this->getSession()->getPage()->find(
+				'css',
+				// Escape CSS selector
+				(false !== strpos($region, "'")) ? str_replace("'", "\'", $region) : $region
+			);
+			if($regionObj) {
+				return $regionObj;
+			}
+		} catch(\Symfony\Component\CssSelector\Exception\SyntaxErrorException $e) {
+			// fall through to next case
 		}
 
 		// Fall back to region identified by data-title.