remove shadow from message bubbles + fix padding

This shadow was not well displayed and a flat design is preferred.

Also, text in bubbles was too close to left border so padding is
increased.

Change-Id: Ib656d385bf54b82e38dcd14b4e96cfcde7c51a84

src/views/IMTableCellView.mm

@@ -40,11 +40,15 @@
     [self.msgView setBackgroundColor:[NSColor clearColor]];
     [self.msgView setString:@""];
     [self.msgView setAutoresizingMask:NSViewWidthSizable];
-     [self.msgView setAutoresizingMask:NSViewHeightSizable];
+    [self.msgView setAutoresizingMask:NSViewHeightSizable];
     [self.msgBackground setAutoresizingMask:NSViewWidthSizable];
     [self.msgBackground setAutoresizingMask:NSViewHeightSizable];
     [self.msgView setEnabledTextCheckingTypes:NSTextCheckingTypeLink];
     [self.msgView setAutomaticLinkDetectionEnabled:YES];
+    [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-5-[msgView]-|"
+                                                                options:0
+                                                                metrics:nil
+                                                                  views:NSDictionaryOfVariableBindings(msgView)]];
    }
 
 - (void) updateWidthConstraint:(CGFloat) newWidth

src/views/MessageBubbleView.mm

@@ -65,7 +65,6 @@
         CGPathAddArcToPoint(outlinePath, nil, maxx, miny, midx, miny, radius);
         CGPathCloseSubpath(outlinePath);
     }
-    CGContextSetShadowWithColor(context, CGSizeMake(0,1), 1, [NSColor lightGrayColor].CGColor);
     CGContextAddPath(context, outlinePath);
     CGContextFillPath(context);