Add plugin activation message; See: websharks/zencache#112

[kristineds]

Add plugin activation message;

• Add plugin activation message that directs users to the settings page to configure/enable ZenCache after activation.

See: wpsharks/comet-cache#112

[jaswrks]

Woohoo! Looks good to me.

[raamdev]

@kristineds Woohoo! Nice work. :-) Could you please make the following changes before I merge this in?

• Remove "page" from "enable page caching" so that it just says "enable caching".
• Change "and configure options" to "and review options"
• For the link to the options page, please make this whole thing a link: "enable caching and review options"

Please post another screenshot here with the changes once you're finished. :-)

[kristineds]

@raamdev @jaswsinc Pls check latest commit changes. :) 1d28f1b

[jaswrks]

Nice. That looks even better.

[raamdev]

@kristineds Reviewed, tested, and merged! Thank you! :-)