Replace ASSERT_EQ(bool,bool) by ASSERT_TRUE/ASSERT_FALSE(bool)

The former now raises gcc warnings:
```
  In file included from .../oce/test/gtest-1.7.0/include/gtest/gtest.h:1929:0,
                   from .../oce/test/STEPImport_test/STEPImport_test.cpp:4:
  .../oce/test/STEPImport_test/STEPImport_test.cpp: In member function ‘virtual void STEPImportTestSuite_testImportAP203_1_Test::TestBody()’:
  .../oce/test/gtest-1.7.0/include/gtest/internal/gtest-internal.h:133:55: warning: converting ‘false’ to pointer type for argument 1 of ‘char testing::internal::IsNullLiteralHelper(testing::internal::Secret*)’ [-Wconversion-null]
       (sizeof(::testing::internal::IsNullLiteralHelper(x)) == 1)
                                                         ^
  .../oce/test/gtest-1.7.0/include/gtest/gtest_pred_impl.h:77:52: note: in definition of macro ‘GTEST_ASSERT_’
     if (const ::testing::AssertionResult gtest_ar = (expression)) \
                                                      ^
  .../oce/test/gtest-1.7.0/include/gtest/gtest_pred_impl.h:166:3: note: in expansion of macro ‘GTEST_PRED_FORMAT2_’
     GTEST_PRED_FORMAT2_(pred_format, v1, v2, GTEST_FATAL_FAILURE_)
     ^
  .../oce/test/gtest-1.7.0/include/gtest/gtest.h:1993:3: note: in expansion of macro ‘ASSERT_PRED_FORMAT2’
     ASSERT_PRED_FORMAT2(::testing::internal:: \
     ^
  .../oce/test/gtest-1.7.0/include/gtest/gtest.h:1994:32: note: in expansion of macro ‘GTEST_IS_NULL_LITERAL_’
                         EqHelper<GTEST_IS_NULL_LITERAL_(expected)>::Compare, \
                                  ^
  .../oce/test/gtest-1.7.0/include/gtest/gtest.h:2011:32: note: in expansion of macro ‘GTEST_ASSERT_EQ’
   # define ASSERT_EQ(val1, val2) GTEST_ASSERT_EQ(val1, val2)
                                  ^
  .../oce/test/STEPImport_test/STEPImport_test.cpp:22:13: note: in expansion of macro ‘ASSERT_EQ’
               ASSERT_EQ(Standard_False,shape.IsNull());
               ^
```