Remove No-check Defaults Options Passed To PTOSC

[paulrrogers]

Defaulting to --no-check-unique-key-change and --no-check-alter may be inappropriate for some users. Dropping these as defaults from OnlineMigrator makes it safer for first-time users and removes one limitation from the README.md. And those who still want them can still set those in their config or PTOSC_OPTIONS.

Since this would technically be a backward incompatible change it should also bump the major version number, if it won't already change for the next release.

[paulrrogers]

Perhaps instead of dropping --no-check-unique-key-change the PTOSC recommended check(s) should be run by OM, unless user explicitly opts into PTOSC's --check-unique-key-change.

If PTOSC checks unique keys by default it will halt progress until user does it anyway, possibly leading to users turning it off without running checks.