Fix article for generator name

Use 'some' instead of 'a/an'.
active_record: Quote numeric values compared to string columns.
Skip schema dumper extensions test if connection does not support it

Travis failed because the postgresql version installed there does not
support extensions, so we just need to skip this for now.
Merge pull request #9207 from dylanahsmith/mysql-quote-numeric

active_record: Quote numeric values compared to string columns.
Merge pull request #9185 from tricknotes/fix-article-for-generator-name

Fix article for generator name
Change behaviour with empty hash in where clause
Merge pull request #9220 from robertomiranda/where-with-empty-hash

Active Record: Change behaviour with empty hash in where clause