Add method to programatically to run DB migration + schema update

[Firefishy]

Description

Currently there seems to be no way to programatically or automatically run a DB migration / schema updates.

Steps to reproduce

1. Install and configure Craft v2.6.2978
2. http://example.com/ works. HTTP 200.
3. Replace files with Craft v2.6.2988
4. http://example.com/ fails with HTTP 503.
5. Run: yiic migrations up
6. http://example.com/ still fails with HTTP 503. All migrations have run, but DB craft_info.schemaVersion is mismatched.
7. http://example.com/admin/ click Update.
8. http://example.com/ works. HTTP 200.

After Step 5 (or using another method) the site should load HTTP 200.
In reality step 3 is by replacing the app container with a new container with the new version.

Additional info

• Craft version: 2.6.2988
• PHP version: 7.1
• Database driver & version: N/A
• Plugins & versions: N/A

[brandonkelly]

Agree that it is weird that running migrate up from the command line will not update the app/plugin schema version once it's done.

[hiasl]

+1 for Craft3: Please provide a command for this last step, otherwise it's hard to do it via Jenkins