Update 'Library Selenium2Library' keyword documentation and examples

[emanlove]

The documentation examples for the Selenium2Library are invalid and wrong. We added another parameter, implicit_wait, to the library initialization but I forgot to update the documentation string.

[emanlove]

We should also update the main library documentation section "Timeouts" with information about the new implicit_wait functionality and a link to the selenium documentation on the topic.

[emanlove]

The documentation examples have been updated but the "Timeouts" section could be improved with information about implicit_wait. Could also add note in "Timeouts" section about why there is, in general, no need for a 'Wait For Page To Load' keyword (See #107). Push completing this issue to 1.2 release.

[emanlove]

Should also add a sentence or two about not setting both timeout and implicit wait to a non-zero value at the same time. See this discussion as to why not.

[aaltat]

Ed, do you feel that this is still valid issue?

[emanlove]

Yes, let's keep this one open. Scheduled for 1.8 release.

[aaltat]

Removed 1,8 milestone because of lack of time.

[pekkaklarck]

These docs have been highly enhanced as part of #924 and enhancements will be part of SL 3.0 rc 1. The latest version of the docs are here at http://robotframework.org/SeleniumLibrary/SeleniumLibrary.html.