Added continuous integration matrix for shared/static library (specified through environment variables).

.travis.yml

@@ -1,9 +1,17 @@
+# Build matrix / environment variable are explained on:
+# http://about.travis-ci.org/docs/user/build-configuration/
 before_install: sudo apt-get install cmake
 language: cpp
 compiler:
   - gcc
   - clang
-script: cmake . && make
+script: cmake -DJSONCPP_LIB_BUILD_SHARED=$SHARED_LIBRARY . && make
+env:
+  global:
+    - JSONCPP_CONTINUOUS_INTERATION=1
+  matrix:
+    - SHARED_LIBRARY=ON
+    - SHARED_LIBRARY=OFF
 notifications:
   recipients:
     - baptiste.lepilleur@gmail.com