Fix infite loop on number example

[WesTyler]

Description

When generating an example value for Joi.number().min().max() in which the min and max values are equal, return the only valid value, which is min.

Related Issue

91

Motivation and Context

When Joi.number() had equal values provided/defaulted for .min() and .max(), the Felicity.example method would hang in an infinite loop expecting min < value && value < max. This patch prevents that loop.

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue. you didn't modify existing tests)

Checklist:

• [x] I have read the CONTRIBUTING document.
• [x] My code follows the Hapi.js style guide.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.