Added calibration values to reading class.
Updated usage for readings to read/update/set new calibration values on each reading.
Added calibration values to toArray method so they appear in detail data feed.
New Observation button selects the current observatory by default
Merge pull request #105 from jdbrown-USGS/GMP-317

New Observation button selects the current observatory by default
adding UserFactory skeleton
Configure user factory skeleton
Add login, logout pages, login.inc.php script to redirect, and updated index to use login.inc.php
Move admin to user table, remove role and user_role tables.
Implement DB connections
Change to single quotes
Move session start below include, capitalize ID and add /index.php to the redirect path
Add /index.php to the redirect path.
When user array is empty, return null
Link to login.css
Add styles for login page.
Add login page to observations
Add login page to observatory
Add admin to mysql user table
Remove password from getCurrentUser()