Use s3 location for eigen download.

BitBucket now uses https which is not supported by CMake external
project.

Applications/ApplicationsLib/CMakeLists.txt

@@ -16,3 +16,7 @@ ADD_CATALYST_DEPENDENCY(ApplicationsLib)
 if(OGS_BUILD_GUI)
 	target_link_libraries(ApplicationsLib PUBLIC Qt4::QtCore)
 endif()
+
+if(TARGET Eigen)
+	add_dependencies(ApplicationsLib Eigen)
+endif()

scripts/cmake/ThirdPartyLibVersions.cmake

 set(OGS_BOOST_URL "http://sourceforge.net/projects/boost/files/boost/1.58.0/boost_1_58_0.tar.bz2/download")
 set(OGS_BOOST_MD5 "b8839650e61e9c1c0a89f371dd475546")
 
-set(OGS_EIGEN_URL "http://bitbucket.org/eigen/eigen/get/3.2.5.tar.gz")
+set(OGS_EIGEN_URL "http://opengeosys.s3.amazonaws.com/ogs6-lib-sources/eigen-3.2.5.tar.gz")
 set(OGS_EIGEN_MD5 "8cc513ac6ec687117acadddfcacf551b")
 
 set(OGS_VTK_VERSION 6.1.0)