Fixed expectations for the change of be_true in RSpec 3.

Compare

    expect(foo).to be true  # 1
    expect(foo).to be_true  # 2

1 means compare with the literal value `true`
2 used to mean "other than nil or false" but was changed to mean
  "returns true to send(:true?)". Instead, one should use
  be_truthy. But that does not work in old RSpec.

So I avoided all that by converting to more specific expectations.

See also
http://bengribaudo.com/blog/2014/01/17/2674/rspec-be-true-be_true-are-different
Fixed quoting backslashed\\family\\names.

Unfortunately the docs for .target.bash_output don't mention proper
quoting yet:
https://github.com/yast/yast-core/blob/3e996f35bbd881ad109223371d10d6e1d1f4e2a5/agent-system/doc/systemagent.md#bash_output
Merge remote-tracking branch 'yast/add-testsuite' into add-testsuite
import String before using it

It worked with "rspec" but not with "rake test:unit", because they run
the tests in a different order and some other test imported String for
us.
Merge remote-tracking branch 'yast/add-testsuite' into add-testsuite