Added toString() methods for better debugging of ignore rules

Change-Id: Ie31687faa2df47ecaacace2504c3b4e93f1ea809
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/fnmatch/CharacterHead.java

 		return c == expectedCharacter;
 	}
 
+	@Override
+	public String toString() {
+		return String.valueOf(expectedCharacter);
+	}
+
 }

org.eclipse.jgit/src/org/eclipse/jgit/fnmatch/RestrictedWildCardHead.java

 	protected final boolean matches(final char c) {
 		return c != excludedCharacter;
 	}
+
+	@Override
+	public String toString() {
+		return isStar() ? "*" : "?"; //$NON-NLS-1$ //$NON-NLS-2$
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/ignore/IgnoreRule.java

 		// We are checking the last part of the segment for which isDirectory has to be considered.
 		return !dirOnly || isDirectory;
 	}
+
+	@Override
+	public String toString() {
+		return pattern;
+	}
 }