* Use container-based CI
* Remove unnecessary CI configuration
* Use Node 6/PostgreSQL 9.6 as default test
… rather than testing 0.10 twice with unspecified PostgreSQL.
* Use `precise` for PostgreSQL 9.1
According to https://docs.travis-ci.com/user/database-setup/, 9.1 isn’t supported on trusty.
* Fix Node 0.10 and 0.12 CI builds
These binaries appear to have been built using g++ with flags that clang doesn’t support. Or something.
Setting PostgreSQL 9.5 as the main version to test against.
NOTE: The following settings are required for 9.5 to work:
```
sudo: required
dist: trusty
```
* Change test matrix in .travis.yml
Add tests for node @ v6. Remove node & postgres test permutations for older versions of node.
* Remove sub-versions
* Remove minor version from node 4
Add a matrix configuration to .travis.yml to test permutations of node and PostgreSQL.
Node versions tested against are v0.10, v0.11, v0.12 and io.js v1.
PostgreSQL versions tested against are 9.1, 9.2, 9.3, and 9.4.
