Upgrade node-pre-gyp to version 0.6.32

The 0.6.32 version of node-pre-gyp supports npm configuration for CA bundles.

Add basic eslint configuration

Upgrade sqlite to 3.15, enable FTS4, FTS5

async: remove racey `uv_ref()`/`uv_unref()`

`uv_ref()` can't be called from the non-event-loop thread. Furthermore,
it is not necessary in `async.h`, because open `uv_async_t` is already
holding the event loop from exiting.

See: #702

[skip travis] AppVeyor: use npm 2.15.9 for node > 0.x to work around "'__pfnDliNotifyHook2': redefinition;"

Appveyor node 0.10.40 fix

Fix interrupt test: wait for exec to complete before continuing with test

Add support for sqlite3_interrupt (with fixed test)