Integration tests for Decimal types

[asfimport]

Reporter: Wes McKinney / @wesm
Assignee: Li Jin / @icexelloss

Related issues:

• [C++] Add JSON read/write support for decimals for integration tests (is blocked by)
• [Java] Add JSON read/write support for decimals for integration tests (is blocked by)
• Implement DecimalArray (is blocked by)
• [Format] In-memory format for 128-bit Decimals, handling of sign bit (is blocked by)
• Completing integration tests for major implemented data types (is a parent of)
• Add decimal type support to ArrowWriter. (is related to)

_{Note: This issue was originally created as ARROW-695. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Removing this from 0.5.0. We first need to resolve the wire format for binary data

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 1048
#1048