fix travis build, upgrading npm version
fix #1148 disable npm spinner on travis

npm 1.4.11+ uses spinner (progress indicator) which messes with the output
of the test suite, making it less readable. There's no need for it during
Travis builds.
feat #1132 Add env. parameter for escapeforhtml

- added templateSettings in EnvironmentSettings
- added hasEscapeHtmlByDefault and setEscapeHtmlByDefault to Environment
- modified Statements.js to check this parameter
- added tests
feat #1132 Add test for env. parameter for escapeforhtml

Made a few changes to the feature implementation, one for code consistency and one for fixing a discrepancy in identifiers use.

The new use case has been tested:

- a template gets compiled with the parameter turned off
- a classical use case is run and checked regarding that
- the parameter is reverted

This required to have two tests, to be able to have two different template compilations. Therefore a bit of refactoring has been done too.

Close #1132
Close #1133
Close #1154