[Python] Ignore files without .parq or .parquet prefix when reading directory of files

[asfimport]

This is a stopgap until we have a chance to implement and test ARROW-528 more thoroughly, and handle other performance optimizations

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

Related issues:

• Arrow release 0.2 (blocks)

_{Note: This issue was originally created as ARROW-545. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
PR: #331

[asfimport]

Uwe Korn / @xhochy:
Issue resolved by pull request 331
#331