Fix #213: Inconsistent naming of CMake options

[ghost]

Summary

Some options have been renamed, most of them have been inverted to avoid double negation. If a deprecated option is used it will override the new one (with proper inversion) and a warning will be printed.

Old name                   Default  |  New name                  Default
------------------------------------+-----------------------------------
CUKE_DISABLE_BOOST_TEST    OFF      |  CUKE_ENABLE_BOOST_TEST    ON
CUKE_DISABLE_GTEST         OFF      |  CUKE_ENABLE_GTEST         ON
CUKE_DISABLE_QT            OFF      |  CUKE_ENABLE_QT            ON
CUKE_DISABLE_UNIT_TESTS    OFF      |  CUKE_TESTS_UNIT           ON
CUKE_DISABLE_E2E_TESTS     OFF      |  CUKE_TESTS_E2E            ON
VALGRIND_TESTS             OFF      |  CUKE_TESTS_VALGRIND       OFF

Example

$  cmake -DCUKE_DISABLE_BOOST_TEST=ON ..

-- The C compiler identification is GNU 8.2.1
-- The CXX compiler identification is GNU 8.2.1
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Deprecation Warning at CMakeLists.txt:31 (message):
  CUKE_DISABLE_BOOST_TEST is deprecated in favor of CUKE_ENABLE_BOOST_TEST
Call Stack (most recent call first):
  CMakeLists.txt:43 (option_depr_message)
  CMakeLists.txt:49 (option_depr_invert)

-- Boost version: 1.68.0
-- Found the following Boost libraries:

. . .

[coveralls]

Coverage remained the same at 62.814% when pulling fd2fcbc605ac39330804f25ae455190e70863497 on sergey-bon:fix-issue-213 into 9ac02a4cf84b082a66415f6b6f2a32867ba70057 on cucumber:master.