client.shared.aexpect: Add NoEchoShellSession

This class behaves the same as ShellSession, additionally it supports
terminals without echo. This could be used eg when interacting with
docker with --tty=false, or when you interact with shell with disabled
echo "stty -echo".

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
client.shared.aexpect: Add send_control function to send ctrl+? sequences

This function helps to map letters to ctrl+letter ascii alternative,
eg. ctrl+c => '\0x03'.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Merge pull request #834 from ldoktor/framework

client.shared.aexpect: Add NoEchoShellSession