WIP - organizing code and writing tests

[brianfoshee]

This PR now does a few things beyond what it was originally opened for:

• Creates a common package which encapsulates MyTime and Reading.
  • main_test.go was renamed `common/myTime_test.go' because that's all it tested
  • Note: run cd comon/ and then run go test -v to run tests for common package
• Creates a db package to encapsulate database related functionality
  • DbManager interface to add and get readings
  • MockDbManager and accompanying test for use in http tests (http tests not implemented) #6
  • Note: run cd db/ and then run go test -v to run tests for db package
• Removes the sqlx package which was being used for db.Select(), in favor of using the builtin database/sql package's functionality for retrieving rows.
• Renames Reading.Temperature to Reading.WaterTemperature #4
• Renames Reading.DeviceId to Reading.DeviceID (per the go lint tool)

Things it needs:

• [x] PostgresDbManager and accompanying tests
• [x] MyTime function for marshalling JSON
• [x] Convert http handlers in main.go to use the AddReading() and GetReadings() functions
• [x] Write tests for the http handlers, using the MockDbManager

Original commit message:

This isn't ready to merge yet (needs testing) but is to remove a 3rd party dependency. the sqlx.Select() function is handy, but using the database/sql package in the stdlib doesn't add any complexity, just some verbosity during the Next() and Scan() actions (these lines https://github.com/crakalakin/aquaponics-data/blob/remove-sqlx/main.go#L59-L76).

After finally understanding the next/scan functions from watching http://www.confreaks.com/videos/3440-gophercon2014-building-database-applications-with-database-sql, I decided this would be a good thing to try.

[brianfoshee]

@letsgitgrowing let me know what you think of the direction of this branch or if you have any questions. Read the updated message above (it originally was not as broad in scope).

[nathanprayzo]

Reviewing branch now.

[brianfoshee]

A handy tip: Instead of needing to cd into each package's directory to run tests, lint, and vet, add ./... to each command's args from the project's root directory and the command will run for each directory which has a package in it. go test ./... go vet ./... golint ./...

[brianfoshee]

@letsgitgrowing the test for GetReadings() look good. I wouldn't worry about testing JSON marshaling in there, though. We can test that in the http handler tests.

Also, let's verify at some point that this issue in the postgres driver package isn't a problem with our inserting a timestamp without timezone column type. The code for that whole repository is an interesting read.

[brianfoshee]

Before this gets squashed/merged let's run go vet, golint and go fmt on all files.

[nathanprayzo]

Whoops, forgot about those tools :)

[brianfoshee]

I just updated the vim-go plugin to the latest version, and it'll now run the goimports tool if you set let g:go_fmt_command = "goimports" in your .vimrc. So it'll run both gofmt on saving a file to format the code, and then it'll import any packages that you need (or remove the ones you're not using).

Did you have any luck with that windows terminal emulator?