Add path parameter sanitization

[sujaygarlanka]

Added path parameter sanitization. So all IDs or other path parameters that should be numeric are checked to be numeric. If they are not, the SDK throws an error. In addition, all IDs that should be alphanumeric are checked to be alphanumeric. If they are not, the SDK throws an error.

[coveralls]

Pull Request Test Coverage Report for Build 2163

• 49 of 60 (81.67%) changed or added relevant lines in 8 files are covered.
• 5 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.01%) to 65.554%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/com/box/sdk/MetadataTemplate.java	2	5	40.0%
src/main/java/com/box/sdk/URLTemplate.java	28	36	77.78%

Files with Coverage Reduction	New Missed Lines	%
src/main/java/com/box/sdk/BoxAPIRequest.java	2	63.51%
src/main/java/com/box/sdk/RealtimeServerConnection.java	3	80.0%

Totals
Change from base Build 2148:	0.01%
Covered Lines:	5498
Relevant Lines:	8387

---

💛 - Coveralls