csvsql: Adds configurable SQL query delimiter.

[sgpeter1]

Sometimes SQL statements in the wild use custom delimiters, other than the standard semicolon ;.

This change adds a new argument to csvsql that applies to queries supplied under --query, --before-insert, and --after-insert.

[coveralls]

coverage: 90.465% (+0.005%) from 90.46%
when pulling 156db8d on sgpeter1:master
into 8fafde0 on wireservice:master.

[jpmckinney]

Thank you!