Revert "COMP: update find_package for boost"

This reverts commit e883243c.

Modules/ThirdParty/Boost/otb-module-init.cmake

 # Required
 message(STATUS "Looking for required Boost headers")
+find_package ( Boost
+  1.35.0
+  REQUIRED
+  )
 
-# Mandatory components
-# - date_time -> ossim plugins
-set(OTB_Boost_COMPONENTS date_time)
 # Optional components
 # Boost (OPTIONAL_COMPONENTS does not work with Boost find_package)
 # unit_test_framework component is used only in GdalAdapters module
 if (BUILD_TESTING)
-  list(APPEND OTB_Boost_COMPONENTS unit_test_framework)
+  set(OTB_Boost_OPTIONAL_COMPONENTS unit_test_framework)
+  message(STATUS "Looking for optional Boost components : ${OTB_Boost_OPTIONAL_COMPONENTS}")
+  find_package ( Boost
+    QUIET
+    1.35.0
+    COMPONENTS ${OTB_Boost_OPTIONAL_COMPONENTS}
+    )
 endif()
-
-#Quiet find package to avoid message "Could not find boost" because unit_testing_framework is not installed
-#message(STATUS "Looking for optional Boost components : ${OTB_Boost_OPTIONAL_COMPONENTS}")
-find_package ( Boost
-  REQUIRED
-  1.35.0
-  COMPONENTS ${OTB_Boost_COMPONENTS}
-  )