Update the version in package.xml to 2.0.0.

Change-Id: Ibac053916520e8c597c875a8c7f5668bb35b6ba1

package.xml

diff --git a/package.xml b/package.xml
index bf5fd8e..e7e3e02 100644
--- a/package.xml
+++ b/package.xml
@@ -30,7 +30,7 @@
 
 <package format="2">
   <name>ceres-solver</name>
-  <version>1.14.0</version>
+  <version>2.0.0</version>
   <description>A large scale non-linear optimization library.</description>
   <maintainer email="ceres-solver@googlegroups.com">
     The Ceres Solver Authors