changed instructions about getting a developer account
changed instructions about getting a developer account

to match what's now on http://kbase.us/developer/, as advised by @shane in https://kbase-jira.atlassian.net/browse/PTV-782.

Also moved ContigFilter to the top of the list of example apps and noted that it's a nice simple starter app to look at.

I did not extensively review the rest of this document, though it might benefit from some revision as we finish revising the more detailed SDK docs. @arman, your comments are welcome as you start to use the SDK!
kbase/kb_sdk,kbaseIncubator/kb_sdk,kbase/kb_sdk,kbase/kb_sdk,kbase/kb_sdk,kbaseIncubator/kb_sdk,kbase/kb_sdk,kbase/kb_sdk,kbase/kb_sdk,kbaseIncubator/kb_sdk,kbaseIncubator/kb_sdk,kbaseIncubator/kb_sdk