Add escaped $ Bourne-style shell prompt support

[mmellin]

This pull request adds proper support by escaping the $ character within the shell prompt variables. This avoids errors when running under normal CLI prompt conditions.

[jnpr-community-netdev]

Can one of the admins verify this patch?

[mmellin]

I guess I didn't create a new branch to split these commit into. Sorry.

Commit fcecf2e is an update to fix an issue with adding the $ prompt. This character seems to need escaping in order for the code to work properly under all conditions.

Commit a9a9c57 is in response to issue #869

[jnpr-community-netdev]

Can one of the admins verify this patch?

[dineshbaburam91]

Fixed using #882 and #934.
Kindly let us know why you required "sleep" in wait_for() definition?

[ntwrkguru]

@dineshbaburam91 The reason for the sleep was literally in the code:

        :param seconds sleep:
           Time to wait after initial call to receive data from buffer. This
           value can help stabilize the output when multiple calls to run()
           are looped but will increase the time spent receiving output.  This
           value can be a floating point number for subsecond precision.

[coveralls]

Coverage decreased (-0.01%) to 93.639% when pulling 83ecfde on mmellin:master into b96f116 on Juniper:master.

[coveralls]

Coverage decreased (-0.02%) to 93.635% when pulling 83ecfde on mmellin:master into b96f116 on Juniper:master.