Limit percent increase when salary is close to upper limit

EV-186

In the front end js refreshes the percent increase to reflect the
actual increase allowed since the salary cannot go above upper limit.
The backend validates the percent increase as well and allows an
increase below the valid ranges only when the current salary is
close to the upper limit.
Simplify code and fix minor decimal issue in web

EV-186

Simplify the code checking in the java class and re-calculate
increase instead of trusting submitted value. Fix order of calculations
in the webpage to make sure the increase is refreshed first before the
salary total.
Fix precision error in js when salary is at high value

EV-186

The js code doesn't store the actual recommended increase. It was
using the rounded down value which caused the salary to not always
reach the high value.
Fix rounding error and bug when saving increase

EV-186
Merge branch 'feature/EV-186-max-percent' into liferay6