Use standard CMake variables - static/shared lib.

Replaced JSONCPP_LIB_BUILD_SHARED => BUILD_SHARED_LIBS

Author: ya1gaurav

.travis.yml

@@ -7,7 +7,7 @@ language: cpp
 compiler:
   - gcc
   - clang
-script: cmake -DJSONCPP_WITH_CMAKE_PACKAGE=$CMAKE_PKG -DJSONCPP_LIB_BUILD_SHARED=$SHARED_LIB -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_VERBOSE_MAKEFILE=$VERBOSE_MAKE . && make && make jsoncpp_check
+script: cmake -DJSONCPP_WITH_CMAKE_PACKAGE=$CMAKE_PKG -DBUILD_SHARED_LIBS=$SHARED_LIB -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_VERBOSE_MAKEFILE=$VERBOSE_MAKE . && make && make jsoncpp_check
 env:
   matrix:
     - SHARED_LIB=ON  STATIC_LIB=ON CMAKE_PKG=ON  BUILD_TYPE=release VERBOSE_MAKE=false