Drop rubypick dependency

What we need is to have `/usr/bin/ruby` executable, which might be
provided by `rubypick` on Fedora, whereas it might be shipped directly
by `ruby` package elsewhere.

run-basic-rails-application/main.fmf

@@ -8,4 +8,4 @@ require:
 - gcc
 - git-core
 - rubygems
-- rubypick
+- /usr/bin/ruby

run-basic-rails-application/runtest.sh

@@ -29,8 +29,8 @@
 # Include Beaker environment
 . /usr/share/beakerlib/beakerlib.sh
 
-PACKAGES=${PACKAGES:-ruby rubygems rubypick}
-REQUIRES=${REQUIRES:-}
+PACKAGES=${PACKAGES:-ruby rubygems}
+REQUIRES=${REQUIRES:-/usr/bin/ruby}
 RUBY=${RUBY:-ruby}
 RAILS=0
 bundle=""