Use a python virtualenv for mozmill and selenium

Also add installation instructions in the README.

README

 Tor Browser Bundle test suite
 =============================
 
+Installation
+------------
+
+To run the test suite, you need perl and the following perl modules:
+
+  Cwd
+  Data::Dump
+  Digest::SHA
+  File::Copy
+  File::Path
+  File::Slurp
+  File::Spec
+  File::Temp
+  FindBin
+  Getopt::Long
+  IO::CaptureOutput
+  IO::Socket::INET
+  Image::Magick
+  JSON
+  LWP::UserAgent
+  Template
+  YAML
+
+If you are using Fedora or other yum based distribution, you can install
+each module with 'yum install perl(ModuleName)'.
+
+The test suite also requires mozmill and python selenium, which we install
+using a virtualenv. You can use the 'setup' script to install them into
+a virtualenv:
+
+  $ ./setup
+
+If you want to reinstall the virtualenv used, remove the 'virtualenv'
+directory and run 'setup' again.
+
+
 Usage
 -----
 
@@ -36,3 +72,8 @@ Available options
 --reports-dir=<directory>
         Directory where the tests reports are saved.
 
+--virtualenv=<directory>
+        Path to the virtualenv where selenium and mozmill are installed.
+        The default is the 'virtualenv' directory created by the 'setup'
+        script.
+

tbb-testsuite

@@ -36,6 +36,7 @@ my %default_options = (
     keyring  => 'erinn.gpg',
     'tor-control-port' => '9551',
     'tor-socks-port'   => '9550',
+    virtualenv => "$FindBin::Bin/virtualenv",
 );
 my $options = get_options(@ARGV);
 sub exit_error {
@@ -46,7 +47,8 @@ sub exit_error {
 
 sub get_options {
     my @options = qw(mozmill! selenium! starttor! tor-control-port=i
-                     tor-socks-port=i reports-dir=s gpgcheck! keyring=s);
+                     tor-socks-port=i reports-dir=s gpgcheck! keyring=s
+                     virtualenv=s);
     my %res = %default_options;
     Getopt::Long::GetOptionsFromArray(\@_, \%res, @options) || exit 1;
     $res{files} = \@_;
@@ -201,7 +203,8 @@ sub mozmill_run {
     my $screenshots_tmp = File::Temp::newdir;
     $ENV{'MOZMILL_SCREENSHOTS'} = $screenshots_tmp;
     my $results_file = "$options->{tbbinfos}{'results-dir'}/$test->{name}.json";
-    system('mozmill', '-b', "$options->{tbbdir}/Browser/firefox", '-p',
+    system("$options->{virtualenv}/bin/mozmill", '-b',
+        "$options->{tbbdir}/Browser/firefox", '-p',
         "$options->{tbbdir}/Data/Browser/profile.default", '-t',
         "$FindBin::Bin/mozmill-tests/tbb-tests/$test->{name}.js",
         '--report', "file://$results_file");
@@ -221,7 +224,8 @@ sub selenium_run {
     return unless $options->{selenium};
     my $result_file = $ENV{SELENIUM_TEST_RESULT_FILE} =
         "$options->{tbbinfos}{'results-dir'}/$test->{name}.json";
-    system("$FindBin::Bin/selenium-tests/run_test", $test->{name});
+    system("$options->{virtualenv}/bin/python",
+        "$FindBin::Bin/selenium-tests/run_test", $test->{name});
     $test->{results} = decode_json(read_file($result_file));
 }