getRequestVar accepts a default value
Added logout method
Uses getInstance() for DB connection
Added the id parameter to read method, created search method

The logs API read() method now accepts a log id. This allows for
a quick way to grab information for a single log. This could
theoretically be done with a combo limit = 1 and offset equal to
some calculated offset, but this is so much easier.

The search method takes a keyword or date as the parameters. It will
search for either one separately or together if both are provided.