gitignore: add missing items

Add items such as libtool, phosphor-certificate-manger,
and test related to the .gitignore.

Change-Id: Iafd8d8b6a47fd2d92cbdf522f3d12151b2ac92c8
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/.gitignore b/.gitignore
index c6198f6..8f3b58d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,6 +28,7 @@
 # https://www.gnu.org/software/libtool/
 
 /ltmain.sh
+libtool
 
 # http://www.gnu.org/software/texinfo
 
@@ -43,4 +44,5 @@
 Makefile
 .deps
 *-libtool
-/phosphor_certificate_manager
+/phosphor-certificate-manager
+test/certs_manager_test