Adding Node.js version 11 to Travis CI test suite

[fishcharlie]

Summary:

This PR adds Node.js version 11 to the Travis CI test suite.

Type (select 1):

• Bug fix
• Feature implementation
• Documentation improvement
• Testing improvement
• Test added to report bug (GitHub issue #--- @---)
• Something not listed here

Is this a breaking change? (select 1):

• 🚨 YES 🚨
• No
• I'm not sure

Is this ready to be merged into Dynamoose? (select 1):

• Yes
• No

Are all the tests currently passing on this PR? (select 1):

• Yes
• No

Other:

• I have searched through the GitHub pull requests to ensure this PR has not already been submitted
• I have updated the Dynamoose documentation (if required) given the changes I made
• I have added/updated the Dynamoose test cases (if required) given the changes I made
• I have run npm test from the root of the project directory to ensure all tests continue to pass
• I agree that all changes made in this pull request may be distributed and are made available in accordance with the Dynamoose license
• All of my commits and commit messages are detailed, explain what changes were made, and are easy to follow and understand
• I have confirmed that all my code changes are indented properly using 2 spaces
• I have filled out all fields above

[coveralls]

Pull Request Test Coverage Report for Build 716

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 85.04%

---

Files with Coverage Reduction	New Missed Lines	%
lib/Table.js	3	76.76%

Totals
Change from base Build 700:	-0.1%
Covered Lines:	1879
Relevant Lines:	2140

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 716

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 85.04%

---

Files with Coverage Reduction	New Missed Lines	%
lib/Table.js	3	76.76%

Totals
Change from base Build 700:	-0.1%
Covered Lines:	1879
Relevant Lines:	2140

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 716

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 85.04%

---

Files with Coverage Reduction	New Missed Lines	%
lib/Table.js	3	76.76%

Totals
Change from base Build 700:	-0.1%
Covered Lines:	1879
Relevant Lines:	2140

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 716

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 85.04%

---

Files with Coverage Reduction	New Missed Lines	%
lib/Table.js	3	76.76%

Totals
Change from base Build 700:	-0.1%
Covered Lines:	1879
Relevant Lines:	2140

---

💛 - Coveralls