Update class-plugin-name.php

Added multisite activation/deactivation functionality.
Update activate_new_site did_action to become Yoda condition
@const is not an official part of PHPDoc

Pointed out by @GaryJones: https://github.com/tommcfarlin/WordPress-Plugin-Boilerplate/commit/4d629b53238b101f71e718f4c41de45997298a69#commitcomment-3943262
Replacing `$this->version` by the new class constant
Merge pull request #58 from thuijssoon/master

Multisite activation / deactivation
Merge pull request #71 from GeertDD/const

Updates related to the new VERSION constant
Merge pull request #74 from nextgenthemes/master

Change default capability to 'manage_options'
removing the lang directory in place of languages
changing the name of the lang directory to languages and all references to it
Initialize plugin on plugins_loaded hook
Merge pull request #76 from barryceelen/patch-1

Initialize plugin on plugins_loaded hook
Removes reference to register_uninstall_hook from code comment

Perhaps mention uninstall.php in stead?

```
// Register hooks that are fired when the plugin is activated or deactivated.
// When the plugin is deleted, the uninstall.php file is loaded.
```
Mention uninstall.php in code comment
Removes 'Change 'plugin-name' to the name of your plugin' from DocBlock

Removes 'Change 'plugin-name' to the name of your plugin' from add_plugin_admin_menu() function DocBlock, as this is now defined via a variable.
Replace plugin-name with $this->plugin_slug in add_action_links()
Merge pull request #79 from barryceelen/patch-2

Removes 'Change 'plugin-name' to the name of your plugin' from DocBlock
Merge pull request #80 from barryceelen/patch-3

Replace plugin-name with $this->plugin_slug in add_action_links()
Merge pull request #77 from barryceelen/patch-1

Removes reference to register_uninstall_hook from code comment
Place options page under 'Settings' in stead of 'Plugins' menu
Merge pull request #81 from barryceelen/patch-1

Place options page under 'Settings' in stead of 'Plugins' menu