Make "/yambas/rest" optional in the base URL

[philippgille]

Always having to include "/yambas/rest" in base URLs is annoying and should be handled automatically.

Implementation proposal:

When the aoms.DefaultClient is instantiated or sends its first request, it should do the following:

1. Check if the baseUrl parameter/field (depending on if this gets implemented for instantiation or first request) contains "/yambas/rest".
   • If it does: Keep it that way.
   • If it doesn't: Add it, because in most cases it's necessary (or maybe currently even mandatory, depending on URL rewrites in ApiOmat and SDK implementations).
2. Probe if the (possibly changed) baseUrl is correct by calling GetVersion() and expecting a version string in the response body. A short timeout should be used and errors should be ignored.
   • If it didn't work, and "/yambas/rest" was previously added manually: Probe again with the original passed baseUrl.
     • If this worked: Use the original baseUrl as base URL.
     • If this didn't work: Ignore, because the probe requests were unsolicited and the caller needs to find out about the error on his own when making the first request.
   • If it worked: Use the (possibly changed) baseUrl as base URL.

Also necessary:

• Add tests to aoms
• Change doc comments and README accordingly