Do not consider a statement as prepared if it errors

Fixes #600
Merge pull request #661 from brianc/issues/600

Do not consider a statement as prepared if it errors
Add regression test for #199
Merge branch 'master' of github.com:brianc/node-postgres
Bump version
Add pg-format to the list of helper modules.
Fix issue with parsed statement cache timing - closes #665
Merge pull request #668 from brianc/issues/600-redux

Fix issue with parsed statement cache timing - closes #665
Bump version
Merge pull request #667 from rpedela/master

Add pg-format to the list of helper modules.
Update README.md
Merge pull request #672 from tlhunter/patch-1

Update README.md
Fix for empty buffer segfault in native bindings
Fix travis environment
Merge pull request #675 from brianc/issues/675

Postgres Native bindings Segfault when querying with empty buffer
Bump version
add pg-transact to readme
Merge pull request #680 from iceddev/master

add pg-transact to readme
Merge with origin/master
Update .travis.yml