Update packages for PETSc and Boost installers.
Produce XML output in unit tests.

.. can be used by Jenkins to present results.
Update in README.
Further improvements of main README.
Add YAML description of Jenkins Jobs.

Preliminary setting provides about the same as curent jobs configuration.
Targets for creating Jenkins jobs from YAML.

Rationale:
- Jenkins build and test jobs configuration stored in the repository.
- adding new integration or unit test should be easy
- consitency in jobs settings

Solution:
- Use template YAML file with placeholders that can be expanded to actual list of
integration and unit tests stored in files 'test_list' 'unit_list' respectively.
- Implement placeholder expansion in cmake (unit_tests/expand_palceholder.cmake)
- Use Jenkins Jobs Builder to produce XML job descriptions from YAML file and upload
  XML files to Jenkins server.

Changes:
- add makefile link in unit_tests (CMakeLists.txt)
- new targets in unit_tests/CMakeLists.txt:
  test-list - make unit_tests/test_list contaioning all tests subdirectories
  jenkins-upload - make YAML from template, produce XML and upload to server
  jenkins-test - make YAML and XML files to build tree
Remove intrusive support for parallel builds.

Remove N_JOBS stuff from main makefile.
We can not set this for all makefiles, all targets either.
README.md has note how to set default parallel builds in .bashrc.
Make unit tests to produce XML files with results.

XML files are produced in the build tree and allows visualisation of results in Jenkins.
Macro to add unit_Test subdirectories.

- add common targets 'all_test' and 'all_bench' into every subdirectory
- make links to generated Makefiles

- we have to allow duplicate targets in main CMakeLists.txt. This works only with Makefile generator.
Fix clean-all to not depend on cmake.
Move script test: bin/tests -> unit_tests/scripts

- fix error in unit_tests/CMakeFile.txt add_test_dir macro
- move bin/tests script unit tests
YAML template for linux debug.

Working YAML template to make complate linux-debug chain.
This chain includes:
configuration, running uni tests, build Flow123d, running integration tests

All within one multi-job.