Change bigint to integer in Postgres schema grammar.

Bigint has too big a range to be returned as an int in PHP. It is returned as a string, which can be confusing and lead to unexpected results. In addition, the range of integer is suitable for most cases: -2147483648 to +2147483647.
Updated unit tests.
Update src/Illuminate/Database/Schema/Grammars/PostgresGrammar.php
Update src/Illuminate/Database/Schema/Grammars/PostgresGrammar.php
fix relationship bug.
remove unneeded var.
tweak interfaces.
Let PostgreSQL use Boolean
Fixed test for PostgreSQL boolean.
Merge pull request #33 from conradkleinespel/patch-1

Change "bigint" to "integer" in Postgres schema grammar.
Merge pull request #76 from philsturgeon/patch-2

Change PostgreSQL to use Boolean
change boolean false to 0.
update composer.json
update connectors to use charset when setting names.
return proper object on __call from relation.
fix type hint.
Tweak __call on Relation base class.
Tweak __call on base relation again. Returns were backwards.
Tweak __call on base relation.
move arrayable to support.