SIO-1735 Add proper LaTeX dependenciees

Added packages instalation instruction to Readme.

Tests passed with packages and crashed (fail or error) without:
oioioi.oireports.tests:TestReportViews:
	test_pdf_report_view (error)
oioioi.mailsubmit.tests:TestMailSubmission:
	test_accepting_mailsubmissions (error)
	test_mailsubmit_permissions (error)
	test_simple_mailsubmission (error)
oioioi.sinolpack.tests:TestSinolPackageInContest:
	test_upload_and_download_package_safe (fail)
	test_upload_and_download_package_unsafe (fail)

Change-Id: I0fff050aeaaa2fb85dbbd6b02b8be86bf002b33a

README.rst

@@ -121,6 +121,7 @@ Ensure that required dependencies are installed:
 * fpc (Ubuntu package: *fp-compiler*)
 * latex with support for Polish (Ubuntu packages: *texlive-latex-base*,
   *texlive-lang-polish*)
+* latex packages (*texlive-latex-extra*, *texlive-fonts-recommended*),
 * lighttpd binary (Ubuntu package: *lighttpd*, shall not be run as service)
 
 and in one terminal run the Django web server::