Dry run script

[krizhanovsky]

For continuous delivery (see #786) we need robust install/uninstall script. Plus to basic test tempesta-tech/tempesta-test#110 it's necessary to run simple test to verify an installation, e.g. run Tempesta with simple config and fake backend, send several requests, and check response. This is very basic check that all the modules are installed correctly. The script doing the checks must be run in the mentioned basic test and a new option for tempesta.sh --dry_run.