Add indents to AST dumping and removed parenthesis from AST nodes.

Add indents to AST dumping and removed parenthesis from AST nodes.
Indents were given the color blue when outputting with color.
AST dumping now looks like this:

Node
|-Node
| `-Node
`-Node
  `-Node

Compared to the previous:

(Node
  (Node
    (Node))
  (Node
    (Node)))

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174022 91177308-0d34-0410-b5e6-96231b3b80d8