Feat: add options.logRequestComplete, allow function syntax for options.logRequestStart

[BlooJeans]

Stacked on top of #89 for formatting improvements to the README

This PR:

• adds the ability to specify the existing options.logRequestStart using a function syntax: (Request) => boolean, which selectively enables/disables the logging on requestStart for the given request

• adds the same functionality for the "request complete" event, letting you pass in either a boolean or a function of the same style.

• keeps the current behavior / defaults, namely:

  • request start events are not logged
  • request completed events are logged

[coveralls]

Coverage increased (+0.1%) to 99.161% when pulling cda5cd8 on devshackio:feat-logRequestStart-logRequestComplete into 890b79e on pinojs:master.

[mcollina]

Would you mind to rebase against master? It currently has a conflict.

[BlooJeans]

Would you mind to rebase against master? It currently has a conflict.

Rebased